Reformed alcohol power systems

ABSTRACT

Improved alcohol reforming processes and reformed alcohol power systems utilizing those processes are disclosed. In preferred embodiments, the alcohol reforming processes utilize a thermally conductive reforming catalyst that allows efficient, low-temperature reforming of an alcohol fuel to produce a reformate gas mixture comprising hydrogen. The present invention makes possible the efficient utilization of alcohol fuels in an internal combustion engine to generate electrical or mechanical power such as in vehicular applications.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority to U.S. Provisional Application No.60/894,635, filed Mar. 13, 2007 and U.S. Provisional Application No.60/813,220, filed Jun. 13, 2006, the entire disclosures of which areincorporated herein.

BACKGROUND OF THE INVENTION

This application claims priority to U.S. Provisional Application No.60/894,635, filed Mar. 13, 2007 and U.S. Provisional Application No.60/813,220, filed Jun. 13, 2007, the entire disclosures of which areincorporated herein.

This invention is generally related to power systems utilizing alcoholreforming, and more particularly, to the efficient reforming of alcoholsto produce hydrogen-containing gas mixtures to use as fuel in internalcombustion engines such as those used to generate electrical ormechanical power in vehicular power systems.

In transportation applications, alcohols, particularly ethanol, aregarnering increased interest as an alternative to fossil fuels forinternal combustion engines. Ethanol is a renewable fuel, typicallyderived from fermentation of agricultural biomass. Unlike fossil fuels,the carbon dioxide liberated during the combustion of ethanol does notrepresent an increase in greenhouse gases because the carbon atomsreleased during combustion represent atmospheric carbon dioxide fixed byplants from which the ethanol is derived.

However, there are difficulties associated with the use of alcohol fuelsin internal combustion engines. The lower heating values of methanol(15.9 MJ/liter) and ethanol (21.3 MJ/L) are substantially less than thatof conventional gasoline (32 MJ/liter) as reported by F. Black in “AnOverview of the Technical Implications of Methanol and Ethanol asHighway Vehicle Fuels,” SAE Paper 912413, 1991. Thus, a greater volumeof alcohol fuel is necessary if utilized with equal efficiency, whichreduces the value of ethanol to the consumer on a volumetric basis.

Moreover, cold start is a problem for alcohol-fueled engines because atlow temperature the fuel lacks sufficient vapor pressure to form anignitable mixture. Anhydrous ethanol engines cannot start at ambienttemperatures below about 15° C. (59° F.). Ethanol, therefore, is usuallyblended with gasoline in the United States (typically, 15% gasoline inE85 blend), so that the gasoline can initiate combustion in coldtemperature operating environments. E85 engines can achieve cold startat low temperatures by massive overfueling in order to force enoughvolatile fuel into the cylinder to achieve ignition. This results inhigh levels of hydrocarbon and carbon monoxide emissions, a problemwhich is significantly aggravated by the fact that the catalyticconverter is not yet at operating temperature. (See J. Ku et. al.,“Conversion of a 1999 Silverado to Dedicated E85 With Emphasis on ColdStart and Cold Driveability”, SAE 2000-01-0590, 2000). Moreover, coldstart problems may persist even using E85 and similar fuel blends atlower temperatures. As a solution to the cold start-up problem, G. W.Davis et al. suggest in Proc. Intersoc. Energy Conver. Eng. Con., 2000,35, pp. 303-8 to supplement the E85/air mixture with hydrogen.

The two most important variables determining the efficiency of aninternal combustion engine are the expansion ratio and the air:fuelratio. The expansion ratio is the ratio of the volume in the cylinder atthe time the exhaust valve opens to the volume at maximum compression.The expansion ratio is often, but not always, equivalent to thecompression ratio. An engine's compression ratio is the ratio of thevolume between the piston and cylinder head before and after thecompression stroke. The air:fuel ratio is sometimes expressed as λ andsometimes as the equivalence ratio, denoted by φ. Lambda (λ) iscalculated by dividing the actual air:fuel ratio by the stoichiometricratio of air:fuel for the fuel being combusted. The equivalence ratio iscalculated by dividing the actual fuel:air ratio by the stoichiometricfuel:air ratio for the fuel being combusted.

Internal Combustion Engine Fundamentals by John B. Heywood (McGraw Hill,New York, 1988) describes the effect of expansion ratio and equivalenceratio on internal combustion engine efficiency. Increasing an engine'sexpansion ratio improves efficiency as does increasing λ. Increasing λabove 1.0 corresponds to using “leaner” fuel-air mixtures (i.e.,mixtures with an excess of air over that required by stoichiometry).

The maximum attainable compression ratio is set by the knock limit.Increasing compression leads to increased temperature and pressure ofthe gas in the cylinder that causes spontaneous, premature ignitionknown as “knock.” The ability of a fuel to resist knock is quantified byits octane number. Both methanol and ethanol are relatively high octanefuels, but methane, hydrogen, and carbon monoxide are more resistant toknock and therefore can be utilized with high efficiency in an internalcombustion engine operated with a high compression or expansion ratio.

Lean combustion improves fuel efficiency in part because it ensurescomplete combustion of the fuel, but primarily by reducing thetemperature of the combusted gas. The lower temperature reduces heatloss to the cylinder walls and improves the thermodynamic efficiencywith which the gas does work on the piston. For example, J. Keller etal. report in SAE Special Publication 1574, 2001, pp. 117-22 thatoperating a four-stroke, spark-ignited internal combustion engine usinghydrogen as a fuel under lean conditions (equivalence ratio=0.35-0.45,corresponding λ=2.2-2.9) and high compression ratio (up to 20) resultsin thermal efficiencies of up to 47%. A further advantage of lowtemperature combustion is the fact that formation of nitrogen oxides(NO_(x)) is minimized.

When the air:fuel ratio becomes too lean (and the gas temperature toocool) the mixture will fail to ignite or “misfire.” Alternatively, themixture may burn too slowly or incompletely. Because hydrogen will burnin air at concentrations down to about 4% and exhibits a high flamevelocity, aiding rapid and complete combustion, supplementation of thefuel with hydrogen allows for reliable operation under lean conditions.As reported by C. G. Bauer et al. in Int. J. Hydrogen Energy, 2001, 26,55-70, the burning speeds of hydrogen, methane, and gasoline in air atnormal temperature and pressure (NTP) are 264-325, 37-45 and 37-43cm/sec, respectively.

Reforming alcohols is an alternative to combusting alcohol fuelsdirectly in an internal combustion engine. In a reforming process, thealcohol is decomposed into permanent gases that can be fed to aninternal combustion engine. L. Pettersson reports in Combust. Sci. andTech., 1990, pp. 129-143, that operating an internal combustion engineon reformed methanol rather than liquid methanol can improve efficiency.The key factors responsible for the improved efficiency are the highair:fuel ratio, the increase in the heat of combustion of reformedalcohols compared to non-reformed alcohols, and the ability to usehigher compression ratios.

It is known that starting an internal combustion engine on a mixture ofpermanent gases produced by methanol reforming is easier than startingon liquid methanol fuel when the ambient temperature is low. Forexample, L. Greiner et al. report in Proceedings of the InternationalSymposium on Alcohol Fuels Technology, 1981, paper III-50, CAS no.1981:465116, that ignition and continuous run at −25° C. can be achievedby reforming methanol using heat from electric current provided by abattery. However, the battery quickly discharges, forcing an early anddifficult transition to the use of liquid methanol fuel and eliminatingany energy efficiency advantage associated with the use of reformedmethanol as a fuel.

In U.S. Pat. No. 4,520,764, issued to M. Ozawa et al. and in JSAEReview, 1981, 4, 7-13, authored by T. Hirota, the use of reformedmethanol to fuel an internal combustion engine at startup and duringsteady-state operation is reported. Engine exhaust is used to heat themethanol reformer. Using lean combustion (λ=1.7) and a high compressionratio (14), they achieved an excellent brake thermal efficiency of 42%.By comparison, the maximum value for non-reformed methanol is about 33%.Ozawa et al. report that the engine can be started on reformate(hydrogen and CO) stored in a pressure vessel.

Reformed methanol power systems tend to backfire severely if thefuel-air mixture is not lean enough because of the high hydrogencomposition. L. M. Das in Int. J. Hydrogen Energy, 1990, 15, 425-43,reports that when the fuel-air mixture is not lean enough, severebackfiring is a problem for engines running on hydrogen. T. G. Adams inSAE Paper 845128, 1984, 4.151-4.157 reports that CO—H₂ mixtures frommethanol reforming backfire at high concentration. As a result, the rateat which fuel can be fed to the engine and the engine's maximum powerare limited.

Vehicular power systems including a fuel cell fed with hydrogen toproduce electrical power have also been suggested. The fuel cell vehiclemay be equipped with pressurized tanks of stored hydrogen or with a fuelprocessor capable of converting an alcohol or other liquid hydrocarbonfuel to hydrogen. Onboard reforming of liquid fuels would enable fuelcell vehicles to achieve ranges comparable to gasoline-fueledautomobiles.

Onboard reforming of liquid or gaseous fuels to yieldhydrogen-containing gas mixtures can be conceptually divided into twocategories depending on the temperature required. It is boththermodynamically and kinetically feasible to reform methanol tohydrogen and carbon monoxide or carbon dioxide with greater than 95%conversion at temperatures of about 300° C. A review of methanolreforming can be found in the article “Hydrogen Generation fromMethanol” by J. Agrell, B. Lindström, L. J. Pettersson and S. G. Järåsin Catalysis-Specialist Periodical Reports, 16, Royal Society ofChemistry, Cambridge, 2002, pp. 67-132. Morgenstern et al. describecomplete conversion of ethanol to methane, hydrogen and CO/CO₂ belowabout 300° C. See U.S. Patent Application Pub. No. 2004/0137288 A1; and“Low Temperature Reforming of Ethanol over Copper-Plated Raney Nickel: ANew Route to Sustainable Hydrogen for Transportation,” Energy and Fuels,Vol. 19, No. 4, pp. 1708-1716 (2005). Although other fuels that reformaround 300° C. are known, such as glycerol, none are abundant enough toserve as motor fuels.

Most other reforming processes are highly endothermic and thereforerequire temperatures of about 700° C. because of the stability ofcarbon-hydrogen bonds in the molecule. Reforming of methane and gasolineas well as high temperature reforming of ethanol to hydrogen and carbonmonoxide are in this category. Although considerable research has beendevoted to onboard generation of hydrogen via high temperaturereforming, fueling an internal combustion engine is not practical athigh reforming temperature, largely because of the energy cost ofgenerating the required heat by burning a portion of the fuel.

By contrast, fueling an internal combustion engine with reformedmethanol is known in the art and is enabled by the fact that thereformer can be maintained at the required temperature (typically about300° C.) by the heat of the engine exhaust. Even so, high thermalconductivity is required in the catalyst and reformer to effectively useengine exhaust as a heat source. Hirota reports in JSAE Review, 1981, 4,7-13, that, although methanol reforming requires a temperature of only300° C., considering the performance of the current reformer's heatexchanger, a temperature difference of about 100° C. between the exhaustand catalyst is required, so that the lower limit of the exhausttemperature is approximately 400° C. This limit corresponds to an enginespeed of about 1400 rpm under no load. Thus, there are difficulties inthe prior art in maintaining reformer temperature (and thus catalystactivity) when the engine is near idle.

Numerous papers have also described the high-temperature steam reformingof ethanol to carbon monoxide and hydrogen using alumina-supported,copper-nickel catalysts in accordance with reaction equation (1) below.In fuel cell power systems, it would be necessary to contact thereformate with a suitable low-temperature water-gas shift catalyst inaccordance with reaction equation (2) to generate further hydrogen andeliminate CO, a fuel cell poison.CH₃CH₂OH(g)+H₂O(g)→2CO+4H₂  (1)water-gas shift: CO+H₂O→CO₂+H₂  (2)

Reaction (1) is highly endothermic, which accounts for the requirementof reforming temperatures of about 700° C. in order to fully convertethanol to hydrogen. The high temperature required for the reactioncauses several difficulties when attempting to utilize ethanol reformedin this way for the generation of electrical or mechanical power. First,as noted above, engine exhaust is not hot enough to supply the heatrequired in the reformer. Accordingly, exhaust-heated, high-temperaturereforming of ethanol for vehicular power system applications has notbeen widely developed or tested. Second, catalyst deactivation duringhigh-temperature ethanol reforming has been reported as severe. Themajor cause of deactivation is coking due to the formation ofpolyethylene on the catalyst surface, which is converted to graphite.The dehydration of ethanol to ethylene, catalyzed by acidic sites on thesupport, is believed to be the root cause of catalyst deactivation. (SeeFreni, S.; Mondello, N.; Cavallaro, S.; Cacciola, G.; Parmon, V. N.;Sobyanin, V. A. React. Kinet. Catal. Lett. 2000, 71, 143-52.) Highlevels of ethylene formation have been reported on alumina-supportedcatalysts (See Haga, F.; Nakajima, T.; Yamashita, K.; Mishima, S.;Suzuki, S. Nippon Kagaku Kaishi, 1997, 33-6.)

Morgenstern et al. have explored fuel cell vehicular power systems fedwith hydrogen produced by the low-temperature (e.g., below about 400°C.) reforming of alcohol, particularly ethanol, over a catalystcomprising copper at the surface of a metal supporting structure (e.g.,copper-plated Raney nickel). Morgenstern et al. propose thatlow-temperature ethanol reforming may be divided into two steps,although a concerted mechanism is also possible. In accordance withreaction equations (3)-(5), ethanol is first reversibly dehydrogenatedto acetaldehyde, followed by decarbonylation of acetaldehyde to formcarbon monoxide and methane. After water-gas shift, 2 moles of hydrogenare produced per mole of ethanol.CH₃CH₂OH(g)→CH₃CHO(g)+H₂ ΔH=+68.1 kJ/mol  (3)CH₃CHO(g)→CH₄+CO ΔH=−19.0 kJ/mol  (4)net after water-gas shift:CH₃CH₂OH+H₂O→CH₄+CO₂+2H₂  (5)

As compared to conventional high-temperature reforming of ethanol, whichproduces 6 moles of hydrogen per mole of ethanol after water-gas shift(reaction equations (1) and (2)), an apparent drawback of thelow-temperature reforming pathway is its low hydrogen yield, producingtwo moles of hydrogen per mole of ethanol after water-gas shift.However, Morgenstern et al. teach that onboard a fuel cell vehicle, themethane in the reformate would pass through the fuel cell unit withoutdegrading its performance and the fuel cell effluent may be fed to adownstream internal combustion engine to capture the fuel value of themethane (along with any residual hydrogen, ethanol and acetaldehyde).Waste heat from the engine exhaust is used to heat the reformer anddrive the endothermic dehydrogenation of ethanol.

Despite the advantages provided in the teaching of Morgenstern et al.and others, the commercial development of vehicular fuel cell powersystems is impeded by the complexity and high cost of the fuel cell unitas well as cold start and transient response issues. Storage of hydrogenonboard the vehicle creates safety concerns and imposes weight and costpenalties associated with the high pressure storage tanks, as well as aloss of energy efficiency caused by the necessity of compressing thehydrogen to pressures of 5-10,000 psi.

Accordingly, a need persists for reformed alcohol power systems invehicular and other applications that use an internal combustion enginefor primary power generation and effectively exploit the fuel value ofalcohols with high efficiency to enable cold start-up without blendingconventional gasoline and allow for leaner air:fuel operation of theinternal combustion engine.

SUMMARY OF THE INVENTION

The present invention is directed to processes for producing mechanicalor electrical power from a fuel comprising alcohol. In one embodiment,the process comprises contacting a feed gas mixture comprising thealcohol fuel with a reforming catalyst in a reforming reaction zone toproduce a product reformate gas mixture comprising hydrogen. Thereforming catalyst comprises a metal sponge supporting structure and acopper coating at least partially covering the surface of the metalsponge supporting structure. The metal sponge supporting structure isprepared by a process comprising leaching aluminum from an alloycomprising aluminum and a base metal. In accordance with one embodiment,the reforming catalyst is prepared by depositing copper on the metalsponge supporting structure. An intake gas mixture comprising oxygen andthe product reformate gas mixture is introduced into a combustionchamber of an internal combustion engine and combusted to produce anexhaust gas mixture. An exhaust gas effluent comprising the exhaust gasmixture is discharged from the combustion chamber and the energy ofcombustion is utilized for the generation of mechanical or electricalpower. The exhaust gas effluent is brought into thermal contact with thereforming reaction zone to heat the reforming catalyst therein.

In accordance with another embodiment of the present invention, aprocess for producing mechanical or electrical power from a fuelcomprising ethanol is provided. The process comprises contacting a feedgas mixture comprising the ethanol fuel with a reforming catalyst in areforming reaction zone to produce a product reformate gas mixturecomprising hydrogen and methane. The reforming catalyst comprises copperat the surface of a metal supporting structure. An intake gas mixturecomprising oxygen and the product reformate gas mixture is introducedinto a combustion chamber of an internal combustion engine and combustedto produce an exhaust gas mixture. An exhaust gas effluent comprisingthe exhaust gas mixture is discharged from the combustion chamber andthe energy of combustion is utilized for the generation of mechanical orelectrical power. The exhaust gas effluent is brought into thermalcontact with the reforming reaction zone to heat the reforming catalysttherein.

A further embodiment of the present invention for producing mechanicalor electrical power from a fuel comprising ethanol comprises contactinga feed gas mixture comprising the ethanol fuel with a reforming catalystcomprising copper in a reforming reaction zone to produce a productreformate gas mixture comprising hydrogen, methane and a carbon oxidecomponent selected from the group consisting of carbon monoxide, carbondioxide and mixtures thereof. The molar ratio of methane to the carbonoxide component in the product reformate gas mixture is from about 0.9to about 1.25 and the rate at which methane is produced in the reformategas mixture is at least about 50% of the rate of ethanol introduced intothe reforming reaction zone on a molar basis. An intake gas mixturecomprising oxygen and the product reformate gas mixture is introducedinto a combustion chamber of an internal combustion engine and combustedto produce an exhaust gas mixture. The energy of combustion is utilizedfor the generation of mechanical or electrical power.

The present invention is further directed to a reformed alcohol powersystem for producing mechanical or electrical power from an alcoholfuel. The process comprises first contacting a feed gas mixturecomprising the alcohol fuel with a reforming catalyst in a reformingreaction zone to produce a product reformate gas mixture comprisinghydrogen. A prechamber gas mixture comprising oxygen and a first portionof the product reformate gas mixture is introduced into a combustionprechamber in fluid communication with a combustion chamber of aninternal combustion engine. An intake gas mixture comprising oxygen anda second portion of the product reformate gas mixture is introduced intothe combustion chamber. The prechamber gas mixture is ignited in thecombustion prechamber to generate a hydrogen-rich flame jet and causecombustion of the intake gas mixture introduced into the combustionchamber, thereby producing an exhaust gas effluent. The energy ofcombustion is utilized for the generation of mechanical or electricalpower.

In another embodiment of the reformed alcohol power system, a feed gasmixture comprising ethanol is contacted with a reforming catalyst in areforming reaction zone to produce a product reformate gas mixturecomprising hydrogen and methane. A prechamber gas mixture comprisingoxygen and a first portion of the product reformate gas mixture or theethanol fuel is introduced into a combustion prechamber in fluidcommunication with a combustion chamber of an internal combustionengine. An intake gas mixture comprising oxygen and fuel is introducedinto the combustion chamber. The prechamber gas mixture is ignited inthe combustion prechamber to generate a flame jet and cause combustionof the intake gas mixture introduced into the combustion chamber,thereby producing an exhaust gas effluent. The energy of combustion isutilized for the generation of mechanical or electrical power.

A still further embodiment of a reformed alcohol power system forproducing mechanical or electrical power from an alcohol fuel comprisescontacting a feed gas mixture comprising the alcohol fuel with areforming catalyst in a reforming reaction zone to produce a productreformate gas mixture comprising hydrogen. An intake gas mixturecomprising oxygen and the product reformate gas mixture is introducedinto a combustion chamber of an internal combustion engine and combustedto produce an exhaust gas mixture. An exhaust gas effluent comprisingthe exhaust gas mixture is discharged from the combustion chamber andthe energy of combustion is utilized for the generation of mechanical orelectrical power. At least a portion of the exhaust gas effluent isrecycled and combined with the intake gas mixture introduced into thecombustion chamber of the internal combustion engine.

A still further embodiment is directed to a process for producingmechanical or electrical power in a power system comprising an internalcombustion engine. The internal combustion engine utilizes a four-strokepower cycle and comprises at least one combustion chamber and an intakevalve in fluid communication with the combustion chamber. The intakevalve has an open and closed position. The internal combustion engine iscapable of producing a combustion chamber expansion ratio that isgreater than the corresponding compression ratio. The process comprisesintroducing an intake gas mixture comprising oxygen and a fuel selectedfrom the group consisting of gasoline, alcohol, reformed alcohol andblends thereof into the combustion chamber of the internal combustionengine. The length of time the intake valve remains in the open positionduring the power cycle is controlled in response to the type of fuelintroduced into the combustion chamber. The intake gas mixture iscombusted in the intake gas mixture and the energy of combustion isutilized for the generation of mechanical or electrical power.

The present invention is further directed to a multi-stage process forreforming an alcohol fuel comprising ethanol. The process comprisescontacting a feed gas mixture comprising the ethanol fuel with areforming catalyst in a first reforming reaction zone at a temperaturebelow about 400° C. to produce a partially reformed gas mixturecomprising hydrogen and methane. The reforming catalyst comprises copperat the surface of a thermally conductive metal supporting structure. Thepartially reformed gas mixture is then contacted with a reformingcatalyst in a second reforming reaction zone at a temperature higherthan the temperature maintained in the first reforming reaction zone toreform methane contained in the partially reformed gas mixture andproduce a product reformate gas mixture comprising additional hydrogen.

Other objects and features of this invention will be in part apparentand in part pointed out hereinafter.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic of a reformed alcohol power system which utilizesonboard storage of reformate gases;

FIG. 2 is a schematic of a reformed alcohol power system suitable forvehicular applications;

FIG. 3 is fragmentary cross-section of a flame jet ignition system usedin the reformed alcohol power system;

FIG. 4 is a schematic of a reformed alcohol power system which utilizesjet ignition suitable for vehicular applications;

FIG. 5 is a schematic of the reformer used in the ethanol reformingactivity study in Example 7;

FIG. 6 is a graphical depiction of predicted NO_(x) emissions forgasoline, hydrogen, ethanol and ethanol reformate internal combustionengine power systems at a high load condition as simulated in Example11;

FIG. 7 is a graphical depiction of predicted exhaust temperatures for anethanol reformate internal combustion engine power system as simulatedin Example 11; and

FIG. 8 is a graphical depiction comparing the predicted peak engineefficiency of an ethanol reformate internal combustion engine powersystem with that of hydrogen, ethanol and gasoline power systems assimulated in Example 11.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

In accordance with the present invention, improved alcohol reformingprocesses and reformed alcohol power systems utilizing those processeshave been devised. The alcohol reforming processes preferably utilize athermally conductive reforming catalyst that allows efficient,low-temperature reforming of an alcohol fuel to produce a reformate gasmixture comprising hydrogen. The present invention makes possible theefficient utilization of alcohol fuels in an internal combustion engineto generate electrical or mechanical power.

Without being bound to any particular theory, the increased efficiencyof preferred embodiments of the disclosed invention is thought to occurby at least three mechanisms. First, the reforming process itself raisesthe lower heating value (LHV) of the fuel. In the case of ethanol, theLHV is raised by about 7%. As the energy required to drive the reformingreaction is provided at least in part by waste combustion exhaust, inpreferred embodiments it is not necessary to use the fuel's heatingvalue to drive the reaction and there is no offset of the increase inthe LHV. Second, the reformate gas mixture is a high octane fuel whichallows high compression ratios to be achieved. Third, the reformate gasmixture can be combusted under lean conditions as the reaction productsare flammable at relatively dilute concentrations. The efficiency gainsof the reforming process are verified by combustion modeling asdescribed in Example 11.

In one preferred embodiment of the present invention,hydrogen-containing gas mixtures for burning in an internal combustionengine are produced by reforming an alcohol fuel in a manner that allowsthe thermal energy demands of the reformer to be satisfied using wasteheat recovered from the engine exhaust. In another preferred embodiment,low-temperature reforming of an ethanol fuel produces a productreformate gas mixture comprising hydrogen and methane, while minimizingdeactivation of the reforming catalyst due to coking. The inventiondisclosed herein provides advantages over other technologies used inexploiting the fuel value of alcohols with high efficiency, includingthe conversion of alcohols to hydrogen via conventional high-temperaturereforming processes and utilization of the hydrogen-containing reformatein fuel cells of vehicular power systems.

A. The Alcohol Fuel

A feed gas mixture comprising an alcohol fuel is contacted with thereforming catalyst in a reforming reaction zone of the reformer.Preferably, the alcohol fuel comprises a primary alcohol such asmethanol, ethanol and mixtures thereof. In accordance with an especiallypreferred embodiment, the alcohol fuel comprises ethanol. The preferredreforming catalyst used in the practice of the present invention isparticularly efficient in the low-temperature reforming ofethanol-containing feed gas mixture, enabling this environmentally andeconomically attractive fuel to be utilized efficiently in a vehicularpower system of relatively modest cost.

The use of a hydrogen-containing gaseous fuel produced from ethanolreforming provides an effective means of starting an ethanol-fueledvehicle at low temperatures, making it unnecessary to blend ethanol withgasoline, as in E85 blended fuels. However, reforming catalysts utilizedin embodiments of the present invention are also useful in the reformingof blended ethanol/gasoline fuels (e.g., E85) as the sulfur in thegasoline portion of the fuel is not liberated during the reformingprocess due to the low temperatures at which the reforming reactionpreferably occurs. Thus, sulfide poisoning of the copper surfaces of thecatalyst does not appreciably occur.

In instances where sulfur poisoning does affect reformer performance,the impact can be minimized by use of low-sulfur gasoline in the blendedfuel mixture. As the gasoline primarily serves as a starting aid,light-end alkanes generally very low in sulfur such as isooctane arepreferred. Alternatively or in addition, a bed of high surface areaRaney copper can be included upstream of the reforming reaction zone toadsorb sulfur and protect the reforming catalyst and, optionally, to actas a preheater and/or evaporator. Raney copper is relatively inexpensiveand can easily be replaced as necessary.

The practice of the present invention allows for use of alcohol fuelsthat contain water. Current ethanol fuels are typically substantiallyanhydrous and a considerable portion of the cost of producing fuel-gradeethanol results from the dehydration step. Moreover, anhydrous ethanol,unlike ethanol containing water, cannot be transported in the existingpipeline infrastructure as the ethanol would ready absorb water presentin the pipeline. Thus, in the practice of the present invention, it isnot necessary to dehydrate the ethanol fuel stock and the cost ofproducing the ethanol fuel can be reduced. Further, use of the presentinvention in vehicular power systems enables ethanol to be distributedvia the current petroleum pipeline infrastructure rather than by railcar.

As noted above, the alcohol fuel used in the feed mixture fed to thereformer preferably comprises ethanol. However, alcohol feed mixturescomprising methanol and methanol-ethanol blends, optionally furthercontaining water, may also be used. In one preferred embodiment of thepresent invention, the alcohol feed mixture comprises an approximately1:1 molar mixture of ethanol and water, or approximately 70% by volumeethanol. In another preferred embodiment of the present invention, thewater content of the alcohol feed mixture comprising ethanol is reducedto no more than about 10% by weight, and even more preferably to no morethan about 5% by weight.

B. Low-Temperature Alcohol Reforming

In accordance with the present invention and described in further detailbelow, alcohol fuel in a feed gas mixture is introduced into thereformer and decomposed into a hydrogen-containing gas over an alcoholreforming catalyst (e.g., a copper-plated Raney nickel catalyst) in thereforming reaction zone. Reaction equation (6) depicts the reforming ofmethanol, while reaction equation (7) depicts the reforming of ethanolin the feed mixture introduced into the reformer. If the feed mixturecontaining the alcohol fuel further contains water (e.g., at least onemole of water per mole of alcohol), the hydrogen content of the of thereformate gas mixture may be enriched by reaction of carbon monoxidewith water to form carbon dioxide and hydrogen via the water-gas shiftreaction shown by reaction equations (8) and (5). The reformingcatalysts described below may exhibit some degree of water-gas shiftactivity or a separate water-gas shift catalyst may optionally beemployed. The hydrogen-containing product reformate gas mixture refersto the gas exiting the reforming reaction zone and following anyoptional water-gas shift reaction.

Methanol

without water-gas shift:CH₃OH→2H₂+CO  (6)net after water-gas shift:CH₃OH+H₂O→3H₂+CO₂  (8)

Ethanol

without water-gas shift:CH₃CH₂OH→H₂+CO+CH₄   (7)net after water-gas shift:CH₃CH₂OH+H₂O→CH₄+CO₂+2H₂  (5)C. The Alcohol Reforming Catalyst

The alcohol reforming reaction is strongly endothermic and efficientheat transfer to the reforming reaction zone is desired for goodconversion. In accordance with preferred embodiments of the presentinvention, mixtures of copper and other metals, particularly mixtures ofcopper and nickel, are used as catalysts for the low-temperaturedehydrogenation (i.e., reforming) of alcohols. Copper-containingcatalysts comprising a thermally conductive metal supporting structure,for example, a catalyst prepared by depositing copper onto a nickelsponge supporting structure, show high activity as catalysts ingas-phase reforming of primary alcohols such as methanol and ethanol.The catalysts used in the practice of the present invention are morestable in and particularly active for the thermal decomposition ofethanol into hydrogen, methane, carbon monoxide and carbon dioxide atlow temperature.

In one preferred embodiment of the invention, the alcoholdehydrogenation or reforming catalyst comprises a copper-containingactive phase or region at the surface of a metal supporting structurecomprising copper and/or one or more non-copper metals. The catalystgenerally comprises at least about 10% by weight copper, preferably fromabout 10% to about 90% by weight copper and more preferably from about20% to about 45% by weight copper. The catalyst may comprise asubstantially homogeneous structure such as a copper sponge, acopper-containing monophasic alloy or a heterogeneous structure havingmore than one discrete phase. Thus, the copper-containing active phasemay be present at the surface of the supporting structure as a discretephase such as a copper coating or an outer stratum; as a surfacestratum, or as part of a homogeneous catalyst structure. In the case ofa copper-containing active phase comprising a discrete phase at thesurface of the supporting structure, the metal supporting structure maybe totally or partially covered by the copper-containing active phase.For example, in a particularly preferred embodiment, the catalystcomprises a copper-containing active phase at the surface of a metalsponge supporting structure comprising nickel. Such catalysts comprisefrom about 10% to about 80% by weight copper and more preferably fromabout 20% to about 45% by weight copper. The balance of the catalystpreferably consists of nickel and less than about 10% aluminum or othermetals by weight. Further, in preferred embodiments wherein the metalsupporting structure comprises nickel, it is important to note thatcopper and nickel are miscible in all proportions. Thus, catalystscomprising a copper-containing active phase at the surface of a nickelsupporting structure may not necessarily have a phase boundary betweenthe copper-containing active phase and the supporting structure.

As is common in catalysis, the activity of the dehydrogenation catalystis improved by increasing the surface area. Thus, it is typicallypreferred for freshly-prepared catalyst comprising a metal spongesupporting structure to have a surface area of at least about 10 m²/g asmeasured by the Brunauer-Emmett-Teller (BET) method. More preferably,the catalyst has a BET surface area of from about 10 m²/g to about 100m²/g, even more preferably the catalyst has a BET surface area of fromabout 25 m²/g to about 100 m²/g, and still more preferably the catalysthas a BET surface area of from about 30 m²/g to about 80 m²/g.

In a certain preferred embodiment for the reforming of ethanol, thesurface of the catalyst preferably contains an amount of nickel atomswhich promote the decarbonylation of aldehydes such as acetaldehyde.Preferably, the surface comprises from about 5 to about 100 μmol/g ofnickel as measured by the method described in Schmidt, “Surfaces ofRaney® Catalysts,” in Catalysis of Organic Reactions, pp. 45-60 (M. G.Scaros and M. L. Prunier, eds., Dekker, New York, 1995). Morepreferably, the surface nickel concentration is from about 10 μmol/g toabout 80 μmol/g, most preferably from about 15 μmol/g to about 75μmol/g.

Importantly, the preferred copper-containing catalysts comprising ametal supporting structure described herein exhibit superior heatconductivity as compared to conventional reforming catalysts comprisingceramic supports. The copper-containing catalysts comprising a metalsupporting structure in accordance with one embodiment of the presentinvention preferably exhibit a thermal conductivity at 300K of at leastabout 50 W/m·K, more preferably at least about 70 W/m·K and especiallyat least about 90 W/m·K.

Suitable metal supporting structures may comprise a wide variety ofstructures and compositions. Preferably, the metal supporting structurecomprises a non-copper metal selected from the group consisting ofnickel, cobalt, zinc, silver, palladium, gold, tin, iron and mixturesthereof, more preferably selected from the group consisting of nickel,cobalt, iron and mixtures thereof. Even more preferably, the metalsupporting structure comprises nickel. Nickel is typically mostpreferred because, for example: (1) nickel is relatively inexpensivecompared to other suitable metals such as palladium, silver and cobalt;(2) combinations of nickel and copper have been shown to promote thedecarbonylation of acetaldehyde to methane and carbon monoxide; and (3)depositing copper onto a nickel-containing supporting structure (e.g.,by electrochemical displacement deposition) is typically less difficultrelative to depositing copper onto a supporting structure containing asignificant amount of the other suitable metals. In such a preferredembodiment, at least about 10% by weight of the metal supportingstructure is non-copper metal. In one particularly preferred embodiment,at least about 50% (more preferably at least about 65%, at least about80%, at least about 85% or even at least about 90%) by weight of themetal supporting structure is non-copper metal. In another embodiment,the supporting structure comprises at least about 10% by weightnon-copper metal and at least about 50% (more preferably from about 60%to about 80%) by weight copper. The non-copper metal may comprise asingle metal or multiple metals. When the metal supporting structurecomprises more than one metal, it is preferred that at least about 80%by weight (more preferably at least about 85% by weight, even morepreferably at least about 90% by weight, and still even more preferablyessentially all) of the metals in the supporting structure are in theform of an alloy.

In an especially preferred embodiment, the supporting structure is ametal sponge comprising copper and/or one or more of the suitablenon-copper metals listed above. As used herein, the term “metal sponge”refers to a porous form of metal or metal alloy having a BET surfacearea of at least about 2 m²/g, preferably at least about 5 m²/g, andmore preferably at least about 10 m²/g. Particularly preferred metalsponge supporting structures have a BET surface area of at least about20 m²/g, more preferably at least about 35 m²/g, even more preferably atleast about 50 m²/g, and still more preferably at least about 70 m²/g.It has been found in accordance with this invention that acopper-containing active phase at the surface of a metal spongesupporting structure results in a material exhibiting the mechanicalstrength, high surface area, high thermal conductivity and density ofthe sponge supporting structure combined with the desired catalyticactivity of the copper. Metal sponge supporting structures can beprepared by techniques generally known to those skilled in the art.Suitable metal sponges include the material available from W.R. Grace &Co. (Davison Division, Chattanooga, Tenn.) under the trademark RANEY aswell as materials generally described in the art as “Raney metals,”irrespective of source. Raney metals may be derived, for example, byleaching aluminum from an alloy of aluminum and one or more base metals(e.g., nickel, cobalt, iron and copper) with caustic soda solution.Suitable commercially-available nickel sponges include, for example,RANEY 4200 (characterized by the manufacturer as having at least 93 wt.% Ni; no greater than 6.5 wt. % Al; no greater than 0.8 wt. % Fe; anaverage particle size in the range of 20-50 μm; a specific gravity ofapproximately 7; and a bulk density of 1.8-2.0 kg/l (15-17 lbs/gal)based on a catalyst slurry weight of 56% solids in water). The metalsupporting structure is preferably substantially free of unactivatedregions and has been washed substantially free of aluminum oxides.Unreacted aluminum tends to react with steam under reforming conditionsto form aluminum oxides which can obstruct diffusion and provide acidsites for ethanol dehydration.

The copper-containing active phase may be deposited at the surface of ametal supporting structure using various techniques well known in theart for depositing metal onto metal surfaces. These techniques include,for example, liquid phase methods, such as electrochemical displacementdeposition and electroless plating; and vapor phase methods such asphysical deposition and chemical deposition. It is important to notethat copper is at least partially miscible with most supportingstructure metals of interest and is completely miscible with nickel.Thus, it has been found that the copper deposition process may result inthe catalyst having copper, or more particularly a copper-containingactive phase or region at the surface of the supporting structure aspart of a discrete phase such as an outer stratum or coating, at thesurface of the supporting structure as part of a surface stratum, orcopper may migrate from the surface of the supporting structure into thebulk of the supporting structure. Without being held to a particulartheory, it is believed that the catalyst surface can move, sinter orotherwise restructure during the reaction conditions of the depositionand alcohol reforming processes resulting in such variations of form inthe copper-containing active phase. Nonetheless, it has been found thatthe copper deposition process results in an overall increase in thecopper content of the catalyst with the deposited copper predominantlypresent at or near the surface of the freshly prepared catalyst, whichis richer in copper than before deposition. A particularly preferredalcohol reforming catalyst comprises a copper-plated Raney nickelsponge, or a copper-plated, copper-doped Raney nickel sponge. Ifcopper-doped Raney nickel is employed as the metal supporting structure,the copper content of the metal sponge is preferably less than about 10%by weight.

The alcohol reforming catalyst does not have to comprise copper coatedon a metal supporting structure (i.e., there may be no discretecopper-containing active phase deposited on or coating the surface ofthe catalyst). Rather, the copper may be mixed with other metals thatprovide desirable properties in a catalyst composition having acopper-containing active phase at the surface thereof. The catalystcomposition may be substantially homogeneous. Preferably, such acatalyst is in the form of a copper-containing metal sponge (e.g., anickel/copper sponge).

Suitable alcohol reforming catalyst compositions for use in the practiceof the present invention and methods and materials for their preparationare described by Morgenstern et al. in co-assigned U.S. PatentApplication Pub. Nos. US 2004/0137288 A1 and US 2002/0019564 A1; U.S.Pat. No. 6,376,708; and in “Low Temperature Reforming of Ethanol overCopper-Plated Raney Nickel: A New Route to Sustainable Hydrogen forTransportation,” Energy and Fuels, Vol. 19, No. 4, pp. 1708-1716 (2005),the entire contents of which are incorporated herein by reference.

While catalysts comprising a metal sponge supporting structure having acopper-containing active phase at the surface as described above areparticularly preferred because of their high thermal conductivity,catalysts comprising an active phase containing copper or mixture ofcopper and nickel at the surface of a non-metallic support may also beused in the low-temperature reforming of alcohol. In this context,non-metallic means not in the metallic state and therefore, for example,not electrically conductive at ambient temperature. Many oxide supportscommonly used for catalysts, such supports comprising alumina (Al₂O₃),lanthanum oxide (La₂O₃), silica (SiO₂), titania (TiO₂), zirconia (ZrO₂),siloxane, barium sulfate and mixtures thereof contain metal atoms, butare thermally and electrically insulating and, accordingly, are notclassified as metals. Carbon supports have some electrical conductivity,but can be considered non-metallic for purposes of this specification.The non-metallic support should be selected so that it is chemicallystable under the conditions of the reforming reaction and exhibits ahigh enough surface area to provide sufficient activity for thereforming reaction. It is typically preferred that freshly-preparedcatalyst comprising a non-metallic supporting structure have a surfacearea of at least about 200 m²/g as measured by theBrunauer-Emmett-Teller (BET) method. Catalysts prepared with anon-metallic supporting structure generally comprises at least about 10%by weight copper, preferably from about 10% to about 90% by weightcopper and more preferably from about 20% to about 45% by weight copper.

Catalysts comprising copper or mixtures of copper and nickel on suchnon-metallic, insulating supports are active for low-temperature alcoholreforming. As shown in Example 9, suitable catalysts can be prepared bycopper plating a nickel catalyst on a non-metallic, insulating supportusing methods similar to those used for copper plating metal spongesupports. Example 10 demonstrates that a copper-nickel catalyst on anon-metallic support (e.g., SiO₂) is active for ethanol reforming aboveabout 200° C., but at elevated temperatures (e.g., above about 220° C.)selectivity is decreased due to the undesired side reaction ofmethanation.

When the alcohol reforming catalyst is prepared by electrochemicaldisplacement deposition of copper onto the surface of the supportingstructure (regardless of whether a metallic supporting structure or anon-metallic, insulating support is utilized), it is particularlypreferable that the surfaces of the support onto which copper isdeposited contain nickel because nickel has several desirablecharacteristics, including: (1) a reduction potential to the metal whichis less than the reduction potential to the metal of copper; (2)relative stability in the alcohol dehydrogenation reaction conditions ofthis invention; (3) greater mechanical strength and resistance toattrition than copper; and (4) nickel/copper catalysts promote thedecarbonylation of acetaldehyde to carbon monoxide and methane.

D. Reformer Design

The alcohol reforming process of the present invention generallycomprises contacting the feed gas mixture comprising the alcohol fuelwith the reforming catalyst in a reforming reaction zone of thereformer. As described in further detail below, the reforming catalystused in the practice of the present invention exhibiting high activityfor low-temperature reforming of alcohols is suitable for incorporationinto a compact and thermally efficient heat exchanger-reformer.

The reforming reaction zone preferably comprises a continuous flowsystem configured to ensure low back-pressure and efficient heattransfer for initiating and sustaining the endothermic reformingreaction. Reformer designs to achieve efficient heat transfer are wellknown and described, for example, by Buswell et al. in U.S. Pat. No.3,522,019 and Autenrieth et al. in U.S. Pat. Nos. 5,935,277 and5,928,614. These patents describe catalytic alcohol reforming reactorsin which heat is supplied to the reforming reaction zone by indirectheat exchange with a heat source through a heat-conducting wall. Heatsources for heating the reforming reaction zone include exhaust gasesfrom the partial oxidation of a portion of the alcohol being reformed orfrom a separate combustion reaction using the alcohol or another fuelsource. As described below, a particularly preferred embodiment of thepresent invention employs exhaust gas effluent discharged from acombustion chamber of a downstream internal combustion engine in whichthe reformate product mixture is burned as the heat source for thereforming reaction zone by bringing the exhaust gas effluent intothermal contact with the reforming reaction zone to heat the reformingcatalyst. When exhaust gases are used as the heat source for heating thereforming reaction zone, the alcohol feed stream and the exhaust streamare preferably not mixed. By not mixing the exhaust and reformatestreams, better control over the air:fuel ratio is achieved in theengine and poisoning byproducts of the thermal and oxidativedecomposition of engine lubricating oil is avoided, but heat transfer isrendered more difficult than would be the case if the gases were simplymixed. Therefore, the catalyst and reformer body are preferablyfabricated from materials possessing high thermal conductivity. For thisreason, the reforming catalysts comprising a copper-containing activephase at the surface of a metallic sponge supporting structure describedherein are particularly preferred in the practice of the presentinvention.

The heat exchanger functions as an alcohol reformer into which a streamof the alcohol feed mixture is fed where it contacts the reformingcatalyst and is heated to reaction temperature by indirect heat transferto the reforming reaction zone. The alcohol feed stream may first beevaporated and at least partially heated to the reforming reactiontemperature in a separate heat exchanger upstream from the reformingreaction zone. In one embodiment, the vaporization of the alcohol feedis conducted in an evaporator heated by coolant circulating through theinternal combustion engine of the reformed alcohol power system.Although vaporization of the alcohol feed can also be accomplished inthe reformer, the use of a separate evaporator avoids the risk thatnon-volatile solutes in the fuel will deposit on the reforming catalyst.In addition, a separate evaporator heated with engine coolantsupplements the vehicle's radiator in maintaining the temperature of theengine coolant.

In one preferred embodiment, the vaporization of the alcohol feed to thereformer is conducted in an evaporator heated by the product reformategas mixture. The evaporator may be separate from or integrated in thesame unit as the reformer. In addition to evaporating the fuel, thisserves to cool the reformate gas mixture prior to introduction into theinternal combustion engine. Reducing the temperature of the reformategas mixture improves engine volumetric efficiency and peak power of aninternal combustion engine fed with the cooled reformate by reducing theamount of air displaced in the cylinder (i.e., combustion chamber) bythe hot gaseous fuel. Optionally, in order to achieve a more compactdesign, the alcohol vaporization and reforming functions may beconducted in a single unit.

In one preferred embodiment, the reformer is designed to achieve rapidand efficient heat transfer from the exhaust of an internal combustionengine to the alcohol feed mixture, allowing the system to beeffectively operated at lower exhaust temperatures, thereby enablingleaner combustion in the engine. In addition, the high thermalconductivity of the preferred metallic reforming catalyst enables morerapid startup of the reformer.

Preferably, the heat exchanger-reformer is constructed so that thethermal pathway by which heat is transferred to the alcohol feed streamis nearly entirely metallic. Preferred metals for the construction ofthe heat exchange surfaces of the reformer that separate the alcoholfeed stream from exhaust of an internal combustion engine or othersuitable heat exchange fluid are those resistant to corrosion,compatible with the reforming catalyst and possess high thermalconductivity. Copper, nickel, and alloys thereof are especiallypreferred metals. Because the use of thin metallic sheets is preferred,the sheets may be reinforced by wire mesh or other means well known inthe art of heat exchanger design, so that the reformer's structure canresist deformation and the effects of vibration (e.g., in vehicularpower system applications). Because copper does not catalyze theformation of soot in the reforming process of the present invention,components of the reformer exposed to the reforming reaction zone arepreferably constructed of materials that contain a copper-rich surface.Likewise, it is also preferred that components upstream of the reformerthat contact the alcohol fuel at elevated temperature, (e.g., componentsof the evaporator or preheater) be constructed having a copper-richsurface. A copper-rich surface can be achieved by using copper-richalloys such as MONEL as the construction material or by plating metals,for example steel, with copper. A process for producing a systemcomponent with a copper surface by copper plating is described inExample 1.

Optionally, a bed of water-gas shift catalyst may be provided downstreamof the reforming reaction zone. The water-gas shift bed is preferablynot in thermal contact with the exhaust gas effluent used to heat thereforming reaction zone since the exit temperature of the reformate istypically adequate to conduct the water-gas shift reaction. Suchcatalysts are well known in the art and compact water-gas shiftcatalytic units suitable for incorporation in vehicular reformers havebeen described by P. Gray and C. Jaffray in “Fuel Cells for AutomotiveApplications,” R. Thring Ed. Wiley, New York, 2004, pp. 61-73 and by B.J. Bowers, J. L. Zhao, D. Dattatraya and M. Ruffo in SAE SpecialPublication 1965 (Applications of Fuel Cells in Vehicles), 2005, pp.41-46.

Incorporation of a water-gas shift catalyst bed is not necessary ifanhydrous alcohol is used as the fuel, nor is it necessary if thereformer is not used onboard a vehicle. For vehicular applications,however, the use of a water-gas shift catalyst bed causes carbonmonoxide in the reformate to be reduced, which may serve to reducecarbon monoxide emissions from the vehicle. However, because thewater-gas shift reaction is exothermic, it reduces the lower heatingvalue of the reformate (e.g., from 317 to 307 kcal/mol for ethanol). Inaddition, the water-gas shift bed adds cost and weight to the vehicle.For these reasons, operation without the water-gas shift bed isgenerally preferred, except in applications where minimizing carbonmonoxide is a concern.

The heat exchanger-reformer is preferably insulated in order to minimizeloss of heat to the environment. This enables the reforming reactionzone to be sufficiently heated using lower temperature exhaust gasesfrom an internal combustion engine of the reformed alcohol power system.The temperature of the reforming catalyst and alcohol feed stream ispreferably regulated by metering the flow of exhaust gases through thereformer by providing two exhaust pathways, one through the reformer andone bypassing it. In engine configurations that utilize exhaust gasrecirculation (EGR), it is preferred to use the cooled exhaust gasstream exiting the reformer as the recirculated gas rather than theexhaust stream which bypasses the reformer. This design allows forincreased volumetric efficiency and is more effective in reducing NO_(x)and improving engine thermodynamic efficiency.

It should be understood that although the alcohol fuel reformingprocesses and reformer designs disclosed herein have particularapplication in reformed alcohol power systems onboard vehicles, thereforming processes and reformers may also advantageously be used instationary applications as well as applications independent of powergeneration, (e.g., in production of reformate fuel).

E. Incorporation of Preferred Catalysts into the Reformer

The metal supporting structure (e.g., metal sponge support),non-metallic or ceramic supports and the alcohol reforming catalysthaving the copper-containing active phase at the surface thereof may bein the form of a powder for packed or fixed bed reformer applications.Alternatively, a fixed bed reformer may utilize a copper-containingcatalyst comprising a metal supporting structure or non-metallic supportin the form of a larger size pellet. Examples of such shaped supportingstructures include the nickel sponge pellets described in EuropeanPatent Application Publication No. EP 0 648 534 A1 and U.S. Pat. No.6,284,703, the disclosures of which are incorporated herein byreference. Nickel sponge pellets, particularly for use as fixed bedcatalysts, are available commercially, for example, from W.R. Grace &Co. (Chattanooga, Tenn.) and Degussa-Huls Corp. (Ridgefield Park, N.J.).Still further, the alcohol reforming catalyst may be used in the form ofa monolith produced by incorporating the catalyst onto the surface of asuitable substrate (e.g., the surface of a non-porous sheet or foil orforaminous honeycomb substrate). Generally, catalyst in the form ofpellets and monoliths are preferred to minimize back-pressure in thereformer. Further, monolithic catalysts may be more stable againstmechanical degradation caused by vibration (e.g., in a vehicular powersystem application) and/or chemical attack in the alcohol reformingreaction medium.

It is important to note that when the catalyst of the invention is usedin the form of a pellet or monolith, it is contemplated that only aportion of the pellet or monolith may comprise a metal sponge ornon-metallic support for supporting the copper-containing active phase.That is, the alcohol reforming catalyst may comprise a non-poroussubstrate to provide strength and shape to a fixed bed or monolithiccatalyst while still providing one or more porous (e.g., metal sponge)regions having a BET surface area of preferably at least about 10 m²/gfor supporting the copper-containing active phase. Suitable non-porousmaterials for use as fixed bed or monolithic substrates generally mayinclude any material that is thermally and chemically stable undercopper plating and reforming conditions. Although non-metal substratesmay be used, metal substrates such as nickel, stainless steel, copper,cobalt, zinc, silver, palladium, gold, tin, iron and mixtures thereofare typically more preferred. Unactivated aluminum and aluminum alloysare preferably avoided in the substrate as they react with ethanol andsteam at the reforming temperature.

When the metal sponge support is in the form of a powder, the preferredaverage particle size of the metal sponge is at least about 0.1 μm,preferably from about 0.5 to about 100 μm, more preferably from about 15to about 100 μm, even more preferably from about 15 to about 75 μm, andstill even more preferably from about 20 to about 65 μm. When thecatalyst is in the form of a pellet or a monolith, the dimensions of thepellet or the monolithic substrate upon which the copper-containingactive phase is incorporated, as well as the size of any foramenalopenings in monolithic structures, may vary as needed in accordance withthe design of the reformer as understood by those skilled in the art.

As shown in Example 2 below, a dry, copper-plated Raney nickel reformingcatalyst in the form of a powder can be prepared such that it packs at adensity of at least about 1.8 g/cm³. The high packing density of such apowder catalyst renders it suitable for use in an onboard fixed bedreformer in vehicular power system applications. Because the metalstructure is hard, attrition is not a significant problem as might arisein the case of catalysts supported on alumina and other non-metallic orceramic supports. Reforming catalyst in the form of pellets and othershaped catalyst are also suitable for fixed bed reformer applications,but typically exhibit lower packing densities and therefore may requirea larger reformer. Generally, selection of a particular reformingcatalyst system and the attendant consequences with respect to reformerdesign will be apparent to those skilled in the art and can be modifiedaccordingly to meet the objectives of a particular application.

To quantify the efficiency of a vehicle running on ethanol (or other)fuels, it is conventional to express the efficiency as the powerproduced divided by the lower heating value of the fuel. In the case ofethanol, the lower heating value is 1235.5 kJ/mol as shown in thereaction equation below.CH₃CH₂OH(l)+3 O₂→2CO₂+3H₂O(g) ΔH_(f)=−1235.5 kJ/Mole

The reformer can be scaled by assuming that the engine mechanical powerout is 35% of the lower heating value of the ethanol fuel. The 35%figure is reasonable in light of the predicted peak efficiency of areformate system as shown in FIG. 8 and described in Example 11 below.

The following calculations illustrate determining the scale required foran onboard fixed or packed bed reformer using a powdered reformingcatalyst such as the catalyst prepared in Example 2. Consider, forexample, a 100 kW vehicle powered by an internal combustion enginerunning on a low-temperature ethanol reformate mixture produced inaccordance with the present invention and comprising hydrogen, methaneand carbon monoxide.

The fuel required at peak power is 13.9 mol/min (639 g/min) asdetermined from the following equation:

${{EtOH\_ flow}\left( \frac{mol}{\min} \right)*1235.5\frac{kJ}{mol}*35\%} = {100\frac{kJ}{\sec}*60\;\frac{\sec}{\min}}$

As described by Morgenstern et al. in “Low Temperature Reforming ofEthanol over Copper-Plated Raney Nickel: A New Route to SustainableHydrogen for Transportation,” Energy and Fuels, Vol. 19, No. 4, pp.1708-1716 (2005) and shown in FIG. 5 a of that publication, 2.5 g ofthis type of powdered catalyst completely reforms 0.1 ml/min of 70%ethanol (0.060 g ethanol/min) at 270° C. with negligible backpressure.The catalyst for those experiments was contained in a 0.375 in. (9.5 mm)internal diameter tube. The cross-sectional area of the inside of thetube is 0.7 cm², thus height of the catalyst bed is approximately 2 cm.

The same Morgenstern et al. publication indicates that the activationenergy for ethanol reforming over copper-plated Raney nickel is 120kJ/mole. For design purposes, a maximum operating temperature for thecatalyst of 350° C. might be assumed, which would increase the activityof the catalyst 30-fold over operation of the catalyst at 270° C. Theminimum exhaust temperature for an engine running on reformed methanolis reported as 350° C. in FIG. 10 of JSAE Review, 1981, 4, 7-13,authored by T. Hirota. Thus, 2.5 g of catalyst could completely reform30×0.06=1.84 g ethanol/min. To provide adequate catalyst for a 100 kWengine at a reforming temperature of 350° C. requires 869 g of catalystin accordance with the following equation:

${Catalyst\_ required} = {\frac{2.5\mspace{14mu} g\mspace{20mu}{catalyst}*639\mspace{14mu} g\mspace{14mu}{{ethanol}/\min}}{{1.84\mspace{14mu} g\mspace{14mu}{{ethanol}/\min}}\mspace{11mu}} = {869\mspace{14mu} g\mspace{14mu}{catalyst}}}$

A 869 g quantity of the powdered catalyst occupies 483 cm³. If the bedheight is 5 cm, in order to minimize backpressure, a disk-shapedreformer packed with a fixed bed of powdered reforming catalyst 11 cm indiameter and 5 cm high is adequate for a vehicle with a 100 kW. Such areformer may be constructed simply by first feeding a feed mixturecomprising ethanol and optionally water to a heat exchanger where it isheated to reforming temperature and then feeding the heated ethanolstream to a packed bed of copper-plated Raney nickel. The ethanol streamis preferably vaporized in the heat exchanger utilizing heat from enginecoolant. In the heat exchanger-reformer, the feed mixture may be heatedto reforming temperature utilizing heat from the exhaust of an internalcombustion engine. The exhaust also supplies the heat required for theendothermic reforming reaction. Preferably, in a fixed bed reformerembodiment, the catalyst and heat exchanger are integrated by packingcatalyst into an insulated container equipped with tubes through whichexhaust passes, supplying heat to the reforming catalyst and the ethanolstream. Integration of the heat exchanger and catalyst improves thermalresponse time. Performance is improved particularly when the vehiclemust accelerate quickly after sitting at idle when the heat availablefrom the engine exhaust is relatively low.

In an embodiment where the alcohol reforming reaction is conducted in afixed or packed bed reformer containing a powdered copper-containingcatalyst as described above, measures may be taken to minimizeback-pressure by, for example, adding an inert solid diluent to thereforming catalyst bed to separate the catalyst particles and maintainspaces between them. The diluent is preferably a material free of acidsites which can catalyze dehydration of ethanol to ethylene and which isthermally stable under the alcohol reforming conditions. Silicon carbideand activated carbon which has not been acid-activated are examples ofpreferred diluents. Alternatively, back-pressure can be minimized byusing a copper-containing catalyst comprising a metal sponge supportingstructure in the form of pellets, rather than powders as describedherein. In a further alternative preferred embodiment, the catalyst maybe used in the form of a monolith produced by incorporating the alcoholreforming catalyst onto the surface of a suitable non-porous orforaminous substrate in order to minimize back-pressure within thereforming reactor.

In one preferred embodiment, the reforming catalyst is present as alayer or film of copper-plated metal sponge catalyst on one side of anon-porous foil or sheet substrate. The sheet is used to form thereforming reaction zone within the heat exchanger-reformer by techniqueswell known in the art, with the catalyst side in contact with the flowof the alcohol feed stream. Thus, the sheet coated with a film of thecopper-plated metal sponge catalyst may be incorporated intoplate-and-frame or spiral-wound heat exchanger designs. Alternatively,the sheets may be formed into tubes for use in a shell-and-tube heatexchanger reformer design. The latter is particularly preferred foralcohol reforming vehicular power applications, because it is compactand thermally efficient.

Sheet or foil substrates having a copper-containing Raney catalystthereon may be produced by depositing, typically by thermal spraying, alayer of a nickel-aluminum or other suitable Raney alloy onto thesubstrate, activating the Raney alloy, and thereafter copper plating theactivated alloy. Preferred Raney alloys for spray deposition onto sheetsubstrates include an approximately 50:50 (wt:wt) alloy of nickel andaluminum. The sheet substrate should be thermally and chemically stableunder, activation, copper plating and reforming conditions and maygenerally comprise nickel, steel, copper or another metal, althoughnon-metal substrates may be used. In order to avoid overly rapid coolingand for improved mechanical strength, the sheet substrate is preferablyat least 20 μm thick. The thickness of the deposited Raney alloy layeror film is preferably from about 5 μm to about 500 μm, more preferablyfrom about 10 μm to about 150 μm. The sprayed sheets are preferablyhandled with minimal bending prior to activation in order to preventdelamination of the layer of Raney alloy deposited thereon. Theproduction of supported metal sponge films is described in U.S. Pat. No.4,024,044; by Sillitto et al. in Mat. Res. Soc. Proc., Vol. 549, pp.23-9 (1999); and by P. Haselgrove and N. J. E. Adkins in Ceramic ForumInternational cfi\Ber. DKG 82 (2005) No. 11 E43-45.

The activation of Raney alloys by treatment with caustic is well knownin the art, particularly for powders, and is readily adapted toactivation of structured Raney alloys. Typically, activation may beachieved by treatment of the alloy with caustic (e.g., 20% NaOH) for twohours at a temperature of about 80° C., as described by D. Ostgard etal. in U.S. Pat. Nos. 6,284,703 and 6,573,213. Activation of Raney alloyon metal sheet or foil substrates is readily accomplished using similartechniques, as further described below in Example 5. The exact method ofactivation is not critical so long as adequate surface area is developedand the handling of the sheets is gentle enough to avoid excessivedelamination of the catalytic layer. Once activated, the sheet or foilsubstrates are quite flexible and can readily mechanically manipulatedand formed into a desired shape for reformer applications. Preferablythe activated sheets are protected from air by, for example, operationunder inert atmosphere or submersion in water before plating the Raneycatalyst layer with copper. For this reason, the Raney alloy film on asheet or foil substrate is preferably manipulated into the desired shapeand assembled into the structure of the reformer after copper plating,and may be performed in ambient air.

Copper plating of Raney alloys coated on metal sheet or foil or othersuitable substrates is preferably conducted by methods similar to thoseknown in the art for Raney metal powders and described in theabove-mentioned publications by Morgenstern et al., includingco-assigned U.S. Patent Application Pub. Nos. US 2004/0137288 A1 and US2002/0019564 A1; U.S. Pat. No. 6,376,708; and “Low Temperature Reformingof Ethanol over Copper-Plated Raney Nickel: A New Route to SustainableHydrogen for Transportation,” Energy and Fuels, Vol. 19, No. 4, pp.1708-1716 (2005). Copper plating of Raney alloy coatings or films onmetal sheet or foil substrates is suitably accomplished by circulatingthe plating bath over the substrate while minimizing bending orvibration of the substrate. Example 6 below describes a suitable methodfor copper plating of an activated Raney nickel alloy film on a nickelfoil substrate by electrochemical displacement deposition. Preferably,the plating will utilize sufficient copper to incorporate from about 2%to about 70% by weight copper into or on the activated Raney layer, morepreferably from about 10% to about 50% by weight copper, and still morepreferably from about 15% to about 40% by weight copper.

Typically, some copper plating of the metallic sheet or foil substratewill also normally occur, unless the exposed side of the substratecomprises essentially pure copper, which is acceptable. Copper platingof the surface of the sheet or foil substrate, which is predominantlyplating of copper onto copper after the first layer of copper isdeposited, is kinetically easier and faster than plating of nickel inthe interior of the Raney metal film. Penetration of copper into theinterior of the Raney metal film during plating is hindered by diffusionand by the fact that the Raney metal (e.g., nickel) surface is likelyoxidized during plating.

Deposition of copper on the exposed side of a metal sheet or foilsubstrate opposite the Raney catalyst coating or film may besubstantially reduced or eliminated by reversibly passivating theexposed side of the substrate prior to copper plating. For example, aninsulating layer may be applied onto the exposed side of the substrateand then stripped from the substrate after the copper plating procedurehas been completed. In one embodiment, an insulating layer comprising anacrylic polymer is spray-applied to the exposed side of the Raney metalcoated substrate and then removed after copper plating, for example, byimmersion in a heated bath of xylenes. Example 8 below describes copperplating of an activated Raney nickel alloy film on a nickel foilsubstrate after first passivating the exposed side of the substrate withan insulating layer. Passivating the exposed side of the substrate priorto copper plating not only conserves copper, but by inhibiting copperfrom depositing on the exposed side of the substrate is believed toenhance penetration and diffusion of copper from the plating bath intothe porous structure of the Raney metal film on the opposite side of thesubstrate rather than being predominantly deposited on the surface ofthe Raney metal layer. Moreover, by causing copper to more deeplypenetrate into the Raney metal structure, it is believed that thistechnique of reversibly passivating the exposed side of the sheet orfoil substrate may also enhance the adhesion the copper-plated Raneyactive layer to the substrate surface and provide a more mechanicallyrobust catalyst structure.

Methods for coating monoliths (e.g., the surface of a non-porous sheetor foil or foraminous honeycomb substrate) with a non-metallic,insulating material to serve as a support for a copper-containingcatalytic active phase of the alcohol reforming catalyst are well-knownin the art. A typical method, used for the preparation of automotiveexhaust catalysts, includes providing an alumina washcoat to provide alayer of non-metallic or ceramic support on the surface of a ceramicmonolith (e.g., honeycomb) as described by R. M. Heck and R. J. Ferrautoin Encyclopedia of Catalysis, vol. 1, I. T. Horvath ed., Wiley, NewYork, pp. 517-60 (2003). Processes for depositing and incorporatingmetals such as nickel and copper onto such washcoated substrates toproduce the alcohol reforming catalyst in the form of a monolith arewidely known by those skilled in the art. While less preferred due totheir generally lower thermal conductivity, non-metallic, insulatorsupported alcohol reforming catalysts have the advantage of beingreadily incorporated into reformers using these well-known commercialtechniques.

F. Reformer Operating Conditions

The temperature of the catalyst and the product alcohol reformate gasmixture or stream may be varied depending on the activity required ofthe catalyst at any point in time. Preferably, however, the reformingtemperature is greater than about 200° C. (below which reforming may beincomplete) and less than about 400° C., since temperatures above thismay require more expensive materials of construction. More preferably,the reforming temperature is from about 220° C. to about 350° C. In thecase of alcohol reforming catalysts comprising a copper-containingactive phase at the surface of a non-metallic supporting structure, thereforming temperature is preferably from about 200° C. to about 220° C.in order to inhibit undesired methanation and maintain selectivity. Thetemperature of the gas mixture within the reforming reaction zone andthe catalyst within the reforming reaction zone are typicallyapproximately the same.

It is preferable to operate the reformer below about 3 atmospheres gaugepressure, primarily because designing the reformer for high pressureoperation entails the use of more expensive or heavier materials ofconstruction (e.g., for the shell and thicker, less thermally conductivesheets of metal coated with alcohol reforming catalyst). The exitpressure from the reformer is preferably sufficient to allow forcontrolled mixing of the reformate gas with air or otheroxygen-containing gas in the preparation of the intake gas (e.g.,fuel-air) mixture for introduction into the combustion chamber of aninternal combustion engine.

In embodiments where the feed gas mixture introduced into the reformingreaction zone of the reformer comprises ethanol, it is preferred thatthe reforming process proceed according to the low-temperature reactionpathway shown in reaction equations (7) and (5) (after optionalwater-gas shift if water is present in the ethanol feed). That is, bymaintaining the reforming temperature within the preferred range,decomposition of ethanol according to the pathway of reaction equation(1), which is dominant in high-temperature steam-reforming systems, doesnot appreciably occur. Thus, it is preferred that the product reformategas mixture produced comprise hydrogen, methane and a carbon oxidecomponent selected from the group consisting of carbon monoxide, carbondioxide and mixtures thereof. Preferably, the methane and carbon oxidecomponents are present in approximately equimolar amounts in the productreformate gas mixture. Molar ratios of methane to the carbon oxidecomponent of from about 0.9 to about 1.25 are approximately equimolar.Moreover, undesired methanation is preferably minimized. An importantadvantage of the preferred reforming catalyst comprising acopper-containing active phase at the surface of a nickel spongesupporting structure is that methanation is negligible under thepreferred operating conditions of the reformer at reforming temperaturesof up to about 400° C.

When the alcohol fuel in the feed gas mixture introduced into thereforming reaction zone comprises ethanol, it is also preferred that therate of methane production in the product reformate gas mixture be atleast about 50% of the ethanol feed rate on a molar basis (i.e., atleast about 50% conversion of ethanol to methane is achieved). Morepreferably, at least about 60% conversion of ethanol to methane isachieved, even more preferably at least about 70% conversion, at leastabout 80% conversion, at least about 90% conversion, and still morepreferably at least about 95% of ethanol in the feed gas mixture isconverted to methane in the reformate gas on a molar basis. The productreformate gas mixture preferably comprises not more than about 10 mole %acetaldehyde and not more than about 20 mole % ethanol, more preferably,not more than about 5 mole % acetaldehyde and not more than about 15mole % ethanol. For catalysts containing a copper-containing activephase at the surface of a metal supporting structure, kinetics aredescribed by Morgenstern et al. in “Low Temperature Reforming of Ethanolover Copper-Plated Raney Nickel: A New Route to Sustainable Hydrogen forTransportation,” Energy and Fuels, Vol. 19, No. 4, pp. 1708-1716 (2005)as being a function of ethanol feed rate, catalyst loading, andtemperature such that reformer conditions can be readily determined andselected based on power system requirements to produce a productreformate gas mixture of the desired composition. Similarly, theseparameters can be adjusted accordingly in the case of other reformingcatalysts comprising a copper-containing active phase at the surface ofa non-metallic supporting structure to produce a product reformate gasmixture of the desired composition.

In another embodiment of the present invention, an alcohol fuel isreformed in a multi-stage reforming process. This concept isparticularly suited for stationary applications for the production ofhydrogen-containing fuels by reforming of alcohols. In a firstlow-temperature stage of the process, the ethanol-containing fuel isintroduced into a first reforming reaction zone and contacted with areforming catalyst as described above comprising copper at the surfaceof a thermally conductive metal supporting structure at a reformingtemperature below about 400° C., preferably from about 220° C. to about350° C., to produce a partially reformed gas mixture comprising hydrogenand methane in accordance with reaction equations (7) and (5) (afteroptional water-gas shift if water is present in the ethanol feed). Thepartially reformed gas mixture from the first reforming reaction zone isthen introduced into a second reforming reaction zone and contacted witha reforming catalyst to reform methane to hydrogen and carbon monoxideand produce a reformate gas mixture preferably substantially free ofmethane. Typically, the second reforming reaction zone of the reformingprocess is a conventional steam reforming stage in accordance withreaction equation (9) and operated at a temperature higher than thetemperature maintained in the first reforming stage.CH₄+H₂O→3H₂+CO  (9)Catalytic steam reforming of methane and other hydrocarbons iswell-known in the art and is typically conducted over nickel-containingcatalysts. The reaction is highly endothermic and high temperatures,generally at least about 700° C., are required in order to obtainacceptable conversions in the second reforming reaction zone.High-temperature steam reforming of hydrocarbons as occurs in the secondreforming stage is discussed by D. E. Ridler and M. V. Twigg in CatalystHandbook, 2nd ed., M. V. Twigg ed. Manson Publishing, London, pp.225-282 (1996), the disclosure of which is incorporated herein byreference.

The overall reforming reaction in the first and second reformingreaction zones is shown in reaction equation (1).

Optionally, a water-gas shift reaction can be employed in such anembodiment resulting in the overall reforming reaction depicted inreaction equation (10).CH₃CH₂OH+3H₂O→2CO₂+6H₂  (10)This multi-stage reforming embodiment reduces coking that occurs inhigh-temperature ethanol steam reformers that operate according toreaction equation (1). The coking is believed to be caused bydehydration of ethanol to ethylene that rapidly forms coke. Withoutbeing bound to any particular theory, it is believed that if the ethanolfuel is first reformed to carbon monoxide, methane and hydrogen at lowtemperature according to reaction equation (7) and the methane furtherreformed to carbon monoxide and hydrogen in a subsequent, highertemperature steam reforming stage according to reaction equation (9),coking can be avoided or substantially reduced. In such a multi-stageethanol reforming process, high-temperature reformate mixture (orportion thereof) exiting the second reforming reaction zone may be usedto supply heat to the low-temperature reformer containing the firstreforming reaction zone.G. Reformed Alcohol Power System Design

The present invention achieves efficient utilization of an alcohol fuelin an internal combustion engine system to produce mechanical and/orelectrical power. The internal combustion engine system may producetorque to drive a vehicle or in combination with a generator produceelectric power. In one embodiment, a feed gas mixture comprising thealcohol fuel is contacted with an alcohol reforming catalyst asdescribed above (e.g., comprising copper at the surface of a thermallyconductive metal supporting structure) in a reforming reaction zone of areformer and reformed to produce a hydrogen-containing product reformategas mixture. An intake gas mixture comprising the resultinghydrogen-containing reformate gas mixture and an oxygen-containing gas(e.g., air), optionally along with non-reformed alcohol fuel, isintroduced into a combustion chamber (i.e., cylinder) of an internalcombustion engine and combusted to generate power and produce an exhaustgas mixture. An exhaust gas effluent comprising the exhaust gas mixtureis discharged from the combustion chamber of the engine and brought intothermal contact with the reforming reaction zone to heat the reformingcatalyst therein to a temperature sufficient to support the alcoholreforming reaction and produce the product reformate gas mixture.

In comparison with an engine fueled with non-reformed, liquid ethanol,internal combustion engines fueled by the hydrogen-containing gasmixture produced by reforming of the alcohol fuel in accordance with thepresent invention can be operated with increased compression ratios andleaner air:fuel ratios. Higher compression ratios can be employedbecause hydrogen, carbon monoxide and methane are far less prone toknock than gasoline. Thus, the engine can be operated more efficiently.

The reformed alcohol power systems of the present invention does notinclude a fuel cell and the hydrogen-containing reformate gas mixture(after optional water-gas shift if water is present in the alcohol feed)is instead combined with air or other oxygen-containing gas to form theintake gas mixture combusted in the internal combustion engine. In orderto maximize the attendant benefits of the hydrogen-containing reformategas mixture as a fuel for the internal combustion engine, it ispreferred that at least about 80% of the hydrogen and other components(e.g., methane in the case of ethanol reforming) obtained in the productreformate gas mixture be introduced into the internal combustion engine.More preferably, at least 90%, at least 95%, or substantially all of thehydrogen and other components obtained in the product reformate gasmixture is utilized as fuel in the internal combustion engine.

Because the power system in accordance with the present invention doesnot include a fuel cell, it is possible to optionally operate the enginewith conventional gasoline instead of an alcohol fuel. This allowsvehicles to be fueled by alcohol, where available, and to be fueled withgasoline if an alcohol fueling station is not available. Further, while,as discussed below, the use of reformed alcohols, particularly reformedethanol, is preferred to the use of liquid, non-reformed alcohols as theprimary motor fuel due to improved efficiency and cold start, operationusing liquid alcohol fuels in a flex-fuel engine utilizing the Miller orAtkinson cycle may be desired. Use of liquid alcohol fuel such asethanol, without reforming, offer slightly improved volumetricefficiencies compared to the use of reformed alcohol fuels.

Flexible fuel operation is achieved by use of the Miller or Atkinsoncycle, which enables an internal combustion engine of a power systemwhich utilizes a four-stroke power cycle to be operated at reducedcompression ratios when gasoline fuel is used and increased compressionratios when an alcohol reformate gas mixture or liquid alcohol fuel isused. The Miller and Atkinson cycles are generally characterized in thatthey enable the expansion ratio to exceed the compression ratio therebyincreasing power system efficiency.

In order to be able to operate on gasoline, reformed alcohol or liquidalcohol fuels, it is necessary to avoid compression ratios that lead toknock. This can be done by operating in the Miller or Atkinson cyclewith adjustments to the timing of the intake valve. In the Miller orAtkinson cycle, the intake valve is left in its open position past theend of the intake stroke (bottom dead center in crank angle space). Asthe piston begins the compression stroke, fuel air mixture is pushed outof the cylinder into the intake manifold through the intake valve.Compression of the gas begins only after the intake valve closes. Thus,when operating on gasoline, it is preferable to close the intake valveat a point that ensures the knock limit is not exceeded. Typically ingasoline blends, especially blends containing 90% by volume gasoline(e.g., E10 or gasoline not diluted by ethanol) the compression ratioshould not be higher than about 10, although this depends on the octanerating of the gasoline.

When reformed alcohol, especially reformed ethanol is used as a fuel,the intake valve is preferably closed earlier, enabling a highercompression ratio to be used. A preferred value is above about 12 and,more preferably, at about 14 (used by Hirota et al. for reformedmethanol).

When alcohol, especially blends containing at least 85% by volumeethanol (e.g., E85 or E100) is used as a fuel, the intake valve ispreferably closed earlier, enabling a higher compression ratio to beused. A preferred value is above about 12 and, more preferably, at about14 (used by Hirota et al. for reformed methanol).

The expansion ratio is not affected by the valve timing adjustment, thusthe system will benefit from the improved efficiencies associated withhigh expansion ratio when utilizing gasoline and reformed alcohol fuels.However, the increased compression ratio used with reformed alcohol fuelincreases the amount of fuel in the cylinder and thus the power.

Preferably, the power system of the present invention is able to controlthe length of time the intake valve remains in the open position inresponse to the type of fuel sent to the combustion chamber(s). Fuelsensors (e.g., polarity or electrochemical sensors) located anywherealong the pathway of fuel from the storage tank to the combustionchamber can by used to determine the type of fuel being sent to thecombustion chambers and can be of the type and design common to flexfuel vehicles presently in operation.

All internal combustion engines operate with highest efficiency in anoptimum range of load and engine speed. Engines operating onhydrogen-rich feeds have relatively wide optima, as shown, for example,in the above-mentioned publications authored by T. Hirota and by Kelleret al. In order to obtain the highest efficiency over the complete drivecycle, reformed alcohol power systems in accordance with this inventionfor vehicular and other applications preferably incorporate technologieswell known in the art for maintaining engine speed and load in theoptimal range over as much of the drive cycle as possible.

Thus, in one preferred mode of operation, the vehicle drive traincomprises a continuously variable transmission or “CVT.” Continuouslyvariable transmissions allow, within limits, the ratio of the wheel ordrive shaft rotational speed to the engine speed to vary continuously.CVTs improve fuel economy by eliminating torque converter lossesassociated with conventional transmissions and by allowing the engine torun at its most efficient speed. A particularly preferred embodimentutilizes the Anderson variable transmission, described in U.S. Pat. Nos.6,575,856 and 6,955,620, the entire contents of which are incorporatedherein by reference.

Other techniques, well known in the art, can be used to maintain theinternal combustion engine at optimum load per cylinder throughout thedrive cycle. One method is to idle some of the cylinders when powerdemand is low. Another is the use of a hybrid electric drive train, ofwhich there are a number of commercial examples, such as the TOYOTAPRIUS or FORD ESCAPE. One or more electric motors are used to supplysupplemental torque when power demand is high. The motors can also beused to generate power via regenerative braking. When power demand islow, excess engine power is used to charge the battery by driving analternator.

Combustion of the gases produced by alcohol reforming in accordance withembodiments of the present invention, specifically CH₄, CO and H₂,counteracts the cold start problem that afflicts systems that combustnon-reformed alcohol fuel directly. In one preferred embodiment of thepresent invention, a supply of reformate gas is maintained onboard thevehicle. This onboard supply can be used to fuel the engine at startupand during subsequent operation until the reformer has attainedoperating temperature and can be used for transient periods of high fueldemand such as acceleration. The fuel is preferably hydrogen orhydrogen-containing alcohol reformate because combustion of these fuelsproduces a clean exhaust, which is not expected to require a catalyticconverter.

An onboard supply of reformate gas may be provided by increasing thesize and pressure rating of the reformer and providing inlet and outletvalves such that a quantity of reformate gas is stored within thereformer when the vehicle is shut down. In such a system, a slowmethanation reaction may occur in the reformer resulting in theproduction of a mixture of CH₄ and CO₂. This configuration alsoincreases the size and weight of the reformer, thereby increasing costand complicating the task of ensuring efficient thermal contact betweenthe exhaust gas stream and the catalyst bed of the reformer.

It is therefore preferable to provide an onboard reformate storage tankand a small compressor that can be used to shunt a small fraction of thereformate to the storage tank as shown in FIG. 1. The reformate shouldpreferably be stored close to ambient temperature in order to increasethe capacity of the storage tank and to improve engine volumetricefficiency resulting from delivery of the reformate to the engine at ahigher density. In addition, avoiding excessive temperatures in thestorage tank prevents the creation of excess pressure that might causethe vessel to rupture. For these reasons, the storage tank is preferablylocated in a region of the vehicle where it is exposed to ambient airand maintained at a lower temperature such as outside the enginecompartment. The storage tank may be equipped with a reliable pressurerelief device as an additional safety feature.

As an alternative to onboard storage of reformate, the catalyst bed inthe reformer can be preheated to the temperature necessary to maintainthe reforming reaction by electric or thermal-chemical source.

FIG. 2 is a schematic of one embodiment of a reformed alcohol powersystem in accordance with the present invention suitable for use invehicular applications. In a preferred embodiment, a turbocharger orsupercharger is employed to pressurize the mixture of air and reformedalcohol fed to the engine and the fuel-air mixture is passed through anintercooler (referred to as Intercooler 2 in FIG. 2) to reduce itstemperature prior to introduction into the cylinder of the engine. It ispreferred to compress the mixture, rather than just air as isconventional for liquid fuels, because this enables the reformer to beoperated close to atmospheric pressure and improves fuel-air mixing. Theuse of compressed fuel-air mixtures as a feed to the engine increasesthe maximum power available from the engine. It is further preferred touse a separate intercooler (Intercooler 1 in FIG. 2) to cool the alcoholreformate prior to blending with air. Cooling of the alcohol reformatecan be accomplished more efficiently than cooling of a reformate-airmixture owing to the higher temperature of the reformate. In a preferredembodiment of the present invention, the alcohol feed is used to coolthe alcohol reformate in Intercooler 1.

As discussed above, the intake valve is preferably left open untilshortly after the beginning of the compression stroke in the cylinder,which has the effect of pushing some of the fuel-air charge back intothe intake manifold. This mode of operation, known as the Miller cycle,is preferred for two reasons. First, gaseous fuels displace volume thatmight otherwise be occupied by air if a liquid fuel were employed. Whenmaximum power is required from the engine, the usual practice is toemploy a roughly stoichiometric air:fuel ratio. When using gaseous fuelssuch as an alcohol reformate, pressurization of the charge is requiredin order to obtain peak power similar to that of a liquid-fueled engine.The second reason is that, without the intercooler, the fuel-air chargewould be hot due to the heat introduced during reforming of the alcoholand turbocharging of the air. The hot charge is more prone to detonateprematurely. Operation without the turbocharger (the Atkinson cycle) orwithout delayed closing of the intake valve are further embodiments ofthe invention, but the former sacrifices some peak power and the lattersome efficiency in comparison to the Miller cycle. Both the Miller andthe Atkinson cycle improve efficiency at part load by eliminatingthrottling losses.

An important advantage of the Miller and Atkinson cycles is that theyenable the engine to be run on conventional gasoline without knock.Typical gasoline formulations will knock at compression ratios above 10,but it is preferable to operate ethanol reformate and liquid ethanolfuel at higher compression ratios in order to improve efficiency. Thus,when gasoline is being used to fuel the engine, it is preferred to leavethe intake valve open longer after the beginning of the compressionstroke in order to reduce the compression ratio to a suitable value forgasoline.

In a preferred embodiment, a power system configured to operate onliquid alcohol fuel, reformed alcohol fuel and mixtures thereof isprovided. The system would include a reformer smaller in size than areformer used in a system which generated power from reformed alcoholalone. In embodiments where ethanol is the reformed fuel, the systemwould typically run on reformed ethanol at startup and at points in thedrive cycle near about 1500 rpm. When higher power is required from theengine, the system would run on non-reformed fuel. This system designhas several advantages over other designs, namely the decreased capitalcost of the smaller reformer, decreased time for the reformer to achieveoperating temperatures sufficient to maintain the reforming reaction andthe ability to achieve high volumetric efficiency without the need toturbocharge. Improved volumetric efficiency also allows for a smallersize of the internal combustion engine. For example, in accordance withone preferred embodiment of the present invention wherein the intake gasmixture comprises ethanol reformate comprising hydrogen and methane andthe non-reformed ethanol fuel, the molar ratio of ethanol to methane inthe intake gas mixture is at least about 10 and in another preferredembodiment, the molar ratio of ethanol to methane in the intake gasmixture is less than about 0.4.

In one preferred embodiment, the engine is spark-ignited. The use ofspark ignition provides more consistent and reliable combustion,particularly when using gasoline as a fuel, and allows engine timing tobe adjusted as the fuel is varied.

In a preferred embodiment, jet ignition is utilized in order to enablereliable ignition and complete combustion to be achieved using reformedethanol fuel at lean air:fuel ratios. Such systems are well known in theart as a technique to extend the engine's lean stable operating limitand are discussed by Heywood in Internal Combustion Engine Fundamentals(McGraw Hill, New York, 1988) on pages 447-50. Ignition occurs in aprechamber cavity, containing the spark source, which is in fluidcommunication with the rest of the cylinder (i.e., to the maincombustion chamber) through an orifice or nozzle. A particularlypreferred embodiment enriches the prechamber with alcohol reformate whenthe engine is operating on a reformed alcohol fuel.

An example of a flame jet ignition system wherein the prechamber gasmixture and combustion chamber intake gas mixture are both supplied fromportions of the product reformate gas mixture is illustrated in FIG. 3.The product reformate gas mixture is produced upstream of the ignitionsystem by contacting a feed gas mixture comprising an alcohol fuel witha reforming catalyst (e.g., catalysts as described above comprising acopper-containing active phase at the surface of a ceramic ornon-metallic support, preferably a metal sponge supporting structure) ina reformer reaction zone.

With reference to FIG. 3, an auxiliary intake passage 1 connects theexit of the reformer to an auxiliary intake valve 2, which is connectedto the prechamber 3 equipped with a spark plug 4. The prechamber 3 is influid communication with the main combustion chamber 5. During intake,the auxiliary intake valve 2 is opened, causing an intake gas mixturecomprising oxygen and a portion of the product reformate gas mixture topass through the prechamber 3 and into the main chamber 5. This resultsin purging of the prechamber. The product reformate gas mixture may,alternatively, be fed to the main chamber 5 through intake valve 7. Theauxiliary valve 2 (and intake valve 7 if used) is closed before thebeginning of the compression stroke. During compression, the leanalcohol reformate gas mixture in the main combustion chamber 5 of thecylinder is forced into the prechamber and preferably bringing theprechamber composition to a composition slightly rich of stoichiometryat the time of the spark discharge. The flame which develops in theprechamber 3 after discharge causes a rise in pressure that, in turn,forces one or more hydrogen-rich flame jets into the main chamber 5,ensuring rapid and complete combustion of the intake gas mixturetherein.

In an especially preferred embodiment, the prechamber gas mixturecomprises ethanol reformate containing hydrogen and methane and theintake gas mixture comprises oxygen and fuel. A variety of fuels may beselected for use in the intake gas mixture, including, for example,alcohol reformate compositions, non-reformed liquid alcohol, liquidalcohol/water blends (e.g., E10 or E85) and gasoline. In embodimentswhere the fuel used in the intake gas mixture is different from theprechamber gas mixture (i.e., is other than ethanol reformate), it ispreferred that the intake gas mixture be delivered to the main chamber 5through intake valve 7 rather than auxiliary intake valve 2.

Fueling of the jet ignition system with liquid fuels, such as ethanoland gasoline, is also feasible, but in that case, the liquid fuel ispreferably supplied to the prechamber via a fuel injector.

FIG. 4 depicts a reformed alcohol power system utilizing jet ignition. Awater-gas shift bed is not included as in the power system depicted inFIG. 2 as it is assumed the vehicle operates on ethanol with a low watercontent and there is no turbocharger. The flow of reformate to the jetand the intake manifold is controlled with variable valves 9, 10. Theremainder of the system operates in accordance with the system shown inFIG. 2 and described herein.

As jet ignition enables lean combustion of alcohols, it is particularlyuseful in a power system configured to operate on both liquid alcoholfuel and a reformed alcohol fuel and which employ a reformer smaller insize than a reformer of a system which generates power from reformedalcohol alone as described above. K. Wakai et al. in Effect of SmallHydrogen Jet Flame on Augmentation of Lean Combustion, SAE Paper 931943,1993, demonstrate the use of hydrogen jet ignition to maintain reliablecombustion of methanol under very lean conditions, for example, with a φequal to about 0.5. Hydrogen jets with a φ equal to 0.5, 1.0 and 2.0were generated by igniting the H₂—O₂ mixture in a prechamber with avolume 1% of the main chamber volume. K. Wakai et al. report that thehydrogen jet igniter reliably ignites the very lean mixture and resultsin faster and more complete combustion.

To achieve the same effect with an ethanol reformate system, a largerprechamber is required due to the significantly slower flame speed.Honda's Compound Vortex Controlled Combustion (CVCC) engine used jetignition with larger prechambers and a relatively fuel-rich gasoline-airmixture. T. Date et al. report the use of prechambers with a volume of4%, 7.3% and 16% of the total combustion volume in Research andDevelopment of the Honda CVCC Engine, SAE paper 740605, 1974. Accordingto the authors the optimum ratio of fuel to the prechamber to total fuelis 40% at idle and 25% at 50 mph.

Thus, reformate supplied through the prechamber is preferably from about5 to about 20% of the fuel value at high load. This results in improvedvolumetric efficiency as compared to a power system where all of thefuel is reformed. At lower loads the reformer can supply a higherfaction of the fuel.

The remainder of the fuel input would be composed of a liquid fuel,preferably an alcohol and most preferably ethanol. The liquid fuel isintroduced through the intake manifold with use of a carburetor ratherthan fuel injection, as this enables use of the Atkinson cycle andprovides the flexibility to use either gasoline or ethanol as liquidfuel.

In accordance with one preferred embodiment, reformed ethanol, inaddition to being used for jet ignition, is added to the intakemanifold. According to E. J. Tully et al. in Lean-Burn Characteristicsof a Gasoline Engine Enriched with Hydrogen from a Plamatron FuelReformer, SAE paper 2003-01-630, 2003 and {hacek over (Z)}. Ivani{hacekover (c)} et al. in Effect of Hydrogen Enhancement on Efficiency and No_(x) Emissions of Lean and EGR-Diluted Mixtures in an SI Engine, SAEpaper 2005-01-0253, 2005, mixtures of gasoline and 15-30% reformedgasoline (CO, H₂, and N₂) with normal ignition are known to burn leanerwith higher efficiency than ordinary gasoline. Similar efficiency gainsare expected in the case of ethanol. One skilled in the art canexperimentally optimize the split between reformed ethanol to the jetand to the intake manifold over the speed and load map.

In another preferred embodiment, the fuel-air mixture is subjected tostratified charge combustion. In a further preferred embodiment, thefuel-air mixture is not spark ignited, but rather ignition is achievedby the use of Homogeneous Charge Compression Ignition (HCCI) asdescribed, for example, by A. O. zur Loye et al. in U.S. Pat. No.6,915,776. HCCI is well known in the art as a method for utilizingwell-mixed fuel-air mixtures, such as those produced in the practice ofthe present invention. High thermal efficiency can be achieved by theuse of HCCI with proper control of operational variables such asequivalence ratio, as set forth by zur Loye et al.

H. Fuel System Operation

1. Normal Operation

Referring again to FIG. 2, a preferred configuration in accordance withthe present invention is illustrated. If the ambient temperature is highenough for adequate volatilization of the alcohol fuel (e.g., aboveabout 15° C. for ethanol), then the power system is started similarly asin a conventional vehicle. Valves V3, V4, V5, V7 and V8 are closed andvalve V6 is fully open. If the vehicle is operating on alcohol fuel,then valve V1 is closed, valve V2 is open, and alcohol is supplied tothe carburetor using the liquid fuel pump. If gasoline is to be used atstartup, valve V1 is open and valve V2 is closed, and gasoline issupplied to the carburetor using the liquid fuel pump. The power systemof FIG. 2 can be designed without a source of gasoline without departingfrom the scope of the present invention.

Regardless of whether alcohol fuel or gasoline is used at startup, theexhaust from the engine is forced through the reformer to heat it to thedesired operating temperature as quickly as possible. When the operatingtemperature is reached, variable valves V6 and V7 are adjustedaccordingly in order to regulate the flow of exhaust gases through thereformer body and maintain the desired operating temperature in thereforming reaction zone contained therein.

2. Startup at Low Ambient Temperatures

When the ambient temperature is too low to reliably start the engine,then the engine is started with valves V1, V2, V3, V4, V7 and V8 closedand valve V6 fully open. Gaseous fuel from the gaseous fuel tank ismetered using valve V5, blended with air and used as the starting fuel.Shortly after the engine has been started, liquid fuel (gasoline oralcohol) is supplied to the carburetor, valve V5 is closed, and normalstartup is resumed.

3. Steady State Operation on Reformed Alcohol Fuel

Once the reformer has reached operating temperature, valve V3 is opened(valve V4 remains closed) and alcohol is pumped into the reformer usingthe reformer pump (not shown). When the pressure in the reformer reachesthe design value, the reformed alcohol gas mixture valve V4 is partiallyopened and, from then on, variable valve V4 is used to meter thereformate gas into the fuel intake system. At this time, the liquid fuelpump is shut off, valves V1 and V2 are closed, and the reformer pump iscontrolled to maintain the desired pressure in the reformer. As shown inFIG. 2, the reformed alcohol gas mixture is passed through a watergas-shift stage containing a suitable catalyst (WGS bed) before thereformate gas is introduced into the fuel intake system. The optionalwater-gas shift catalyst bed may be omitted if desired, for example whenthe alcohol fuel comprises anhydrous ethanol.

Optionally, during steady state operation, some of the reformed gas maybe used to recharge the gaseous fuel tank using the compressor andopening valve V8. If operated in this manner, it is preferable to use analcohol fuel containing less than one mole of water per mole of alcoholto avoid condensation of water in the gaseous fuel tank.

4. Idle Operation on Reformed Alcohol Fuel

As can be see from FIG. 7, predicted engine exhaust temperatures at lowidle are less than those at greater power demand. Thus it may bedesirable for the engine exhaust to bypass thermal contact with thereformer at idle conditions so as to not cool the catalyst bed.According to one preferred embodiment, V6 is closed and V7 opened duringidle conditions such that the exhaust by-passes the reformer.

5. Steady State Operation on Gasoline

If the alcohol fuel tank is empty, the system continues to operatefueled by gasoline supplied by the gasoline pump to the carburetor.

It will be appreciated by one skilled in the art that the presentinvention can be used in conjunction with a wide range of engine anddrive train technology beyond that which has been described. Forexample, the use of rotary engines, direct injection of alcohol orgasoline into the cylinders, the induction of swirl in the cylinder toimprove speed of combustion, and the use of other engine cycles, such asthe Westport cycle are all feasible using alcohols reformed inaccordance with the present invention.

While it is preferred that the reformed alcohol system design andoperation of the fuel system be performed with alcohol reformingcatalysts described herein, such designs and operations are not limitedto such catalysts and are compatible with other reforming catalysts.

The following examples are simply intended to further illustrate andexplain the present invention. This invention, therefore, should not belimited to any of the details in these examples.

EXAMPLE 1 Copper Plating of a Stainless Steel Preheater for EthanolReforming

This Example describes copper plating of a preheater used to heat anethanol stream upstream of the catalyst bed in order to suppress sidereactions catalyzed by the steel. The preheater consists of avertically-mounted length of 316 stainless steel tubing (½″ o.d. (1.27cm), ⅜″ i.d. (0.95 cm)) heated with a coil heater. In operation, ethanolis pumped through a tube (⅛″ o.d. (0.32 cm)) also wrapped around theheater. The ethanol then passes upward through the preheater. The heateris controlled with a temperature controller which senses the temperatureof gas exiting the preheater.

The copper plating was applied to a 316 SS preheater tube (100 g) usinga peristaltic pump to circulate a simple copper-plating bath through it.The bath was composed of CuCl₂ (5.37 g) acidified with concentrated HCl(15 g) in deionized water (135 g) in order to remove oxides and allowthe entire interior surface of the tube to be plated. The bath containeda total of 2 g of copper metal. The mixture was circulated through thebath for two hours. The blue color faded and was replaced by deep green,likely due to nickel displaced by copper. A rough, but uniform copperdeposit was seen inside the tube.

EXAMPLE 2 Scaled Up Copper Plating of Nickel Sponge with Drying

This example demonstrates that copper plating of a nickel sponge supportby electrochemical displacement deposition can be effectively conductedat high solids loading. The use of high solids loading reduces the costof catalyst production by improving the productivity of the process andreducing the volume of wastewater. In order to further reduce cost, theamount of copper used in the second (acidic) step of the plating processhas been decreased from 25% to 10% of the nickel sponge substrate mass.

The amount of NaOH used was reduced from 1.5 equivalents to 1.0equivalents (based on the amount copper in the plating bath). Enoughgluconic acid buffer was used to supply the protons required todisproportionate the Cu₂O formed in the first step:Cu₂O+2H⁺→Cu²⁺+Cu⁰+H₂O

This example further shows that the copper-plated nickel sponge catalystcan be dried and safely handled thereafter. When dry, the catalyst doesnot exhibit pyrophoric behavior. Use of a dust mask in handling drycatalyst is recommended.

Raney nickel powder (673 g, grade 4200) was weighed out by Archimedes'method in a 4-liter beaker using a density factor of 1.16. In the firststep of the plating process, CuSO₄.5H₂O (661 g, 25% by weight copperwith respect to substrate; mixture of material from VWR andMallinckrodt) and Versene 100 (2911 g, 1.1 equiv. of Na₄EDTA, Dow viaSpectrum) were combined and stirred to dissolve the copper sulfate. Thesupernatant was decanted from the Raney nickel and the copper-EDTAmixture added. Next, 50% NaOH (212 g, 1.0 equiv.) was added dropwiseover 38 minutes while stirring with an overhead stirrer. The pH rosefrom 9.1 to 11.6. At the end of the addition, the slurry occupied 3.4liters for a substrate weight:volume ratio of 19.8%.

The deep blue supernatant was decanted and the beaker wrapped withheating tape. In the second step of the plating process, 50% gluconicacid (1038 g, 1.0 equiv with respect to copper added in the first step,Spectrum) and water (1 liter), both heated, were added to the beaker andstirring initiated. A solution of CuSO₄.5H₂O (264 g, 10% by weightcopper with respect to substrate) in water (1 liter) was added dropwiseover 82 minutes with continuous stirring and heating. The pH fell from3.3 to 2.4. The initial and final temperatures were 56° C. and 70° C.,respectively. The final volume was 3.4 liters, matching that in thefirst step.

The blue-green supernatant was decanted and the catalyst rinsed twicewith deionized water. The rinse was conducted by adding water to aslurry volume of 3.4 liters, stirring briefly, and then settling thecatalyst and decanting the supernatant. The second rinse had a pH of 4.0and was clear. The catalyst was initially a bright copper color, butpartially darkened to a copper brown color during the decantation.

The catalyst was then transferred to an 800 ml beaker where it occupied350 ml. It was dried overnight at 120° C. under 24″ Hg (610 mm Hg)vacuum with nitrogen purge. The copper-colored catalyst was transferredin air to a bottle. Some heating occurred and a few sparks wereobserved. 679 g of catalyst were recovered.

In order to allow the catalyst surface to be passivated by oxygen in acontrolled way without overheating, the bottle of catalyst wasevacuated, backfilled with argon and loosely capped. The catalyst bottlewas placed in a beaker of water to cool the bottle as air slowly enteredthe catalyst bottle. The catalyst color dulled slightly. After half anhour, the bottle was removed from the water bath. The cap was left loosefor another hour, but no heating was observed, so the bottle was cappedfor storage. No heating or further change in catalyst color was observedwhen the catalyst was stored in air at room temperature.

Elemental analysis of the dried catalyst by Inductively Coupled PlasmaMass Spectrometry (ICP-MS) determined that its composition to be: 67.8%Ni, 29.6% Cu, and 2.7% Al. The dried catalyst packed at a density of 1.8g/cm³.

EXAMPLE 3 Ethanol Reforming with and without a Copper Plated Preheater

Anhydrous ethanol was reformed over dry copper-plated Raney nickel (2.5g) produced by the process of Example 2 at 280° C. at a feed rate of0.07 ml/min. The preheater used upstream of the catalyst bed was notcopper plated. Coking caused backpressure to develop in the preheater,forcing the experiment to be terminated after 36 hours.

The plugged preheater was replaced by a copper-plated stainless steeltube prepared by the process of Example 1. Anhydrous ethanol wasreformed for 118 hours with the same catalyst at a temperature of 280°C. at a flow rate of 0.07 ml/min. The catalyst was not replaced. Cokingwas not observed. Pressure remained below 3 psig (144 mm Hg gauge)Ethanol breakthrough rose from 4% to 16% over the first 75 hours andthen leveled off.

EXAMPLE 4 E85 Reforming with a Copper Plated Preheater

The experiment in Example 3 was conducted but the feed was changed to asimulated E85 fuel. The E85 simulant was a mixture of 85% absoluteethanol and 15% n-pentane on a volume basis (8.2% pentane on a molarbasis). Pentane passed through the reformer without reaction. No newpeaks were seen by gas chromatography and the exit concentration ofpentane was 8%, indicating that pentane was not consumed. The experimentwas continued to a total run time of 125 hours (200 total hours with 75hours being the copper-plated run of Example 3). Pressure remained below3 psig (155 mm Hg gauge) and slow deactivation continued with ethanolbreakthrough reaching about 21% at the end of the run.

EXAMPLE 5 Activation of a Raney Nickel Alloy Film

This example describes the activation of a film of Raney nickel alloy(50% aluminum, 50% nickel) coated on a 38 μm nickel foil (CERAM,Stoke-on-Trent, Great Britain). The nominal loading of Raney nickelalloy on the foil was 0.070 g/cm². The Raney nickel alloy-coated foilswere 12 cm in width and cut to 30-40 cm lengths. The preparation of theRaney alloy-coated metal foils is described by P. Haselgrove and N. J.E. Adkins in Ceramic Forum International cfi\Ber. DKG 82 (2005) No. 11E43-45.

The activation was conducted in a glass developing tank (7 cm×27.5 cm incross section) for thin layer chromatography. To avoid the necessity ofbending the Raney nickel alloy-coated foil, a piece (31 cm long and 12cm wide) was cut in two (17 cm×12 cm and 14 cm×12 cm) and the two piecesplaced in the glass developing tank. The initial weight of the Raneynickel alloy-coated foil was 38.76 g. The total quantity of Raney alloyon the foil was calculated to be 26 g. Ice (1100 g) was added to thetank followed by 50% NaOH (400 g). Water (1200 ml) was added to raisethe water level above the top of the film.

The foil was kept in the tank for six hours during which the bath warmedto room temperature and hydrogen evolution was steady. The color of theRaney nickel alloy film darkened conspicuously. After the six hourslapsed, the liquid was drained from the tank and replaced by water(approximately 2 liters at 85° C.) which promoted bubbling despite theabsence of base, followed immediately by the addition of 50% NaOH (200g). Gas evolution increased dramatically after base addition, but therewas no foaming. Gradually, gas evolution decreased. After 20 minutes,additional 50% NaOH (600 g) was added to the tank. This led to anincrease in hydrogen evolution similar to that which occurred during thefirst base addition. An hour after the first base addition, hydrogenevolution had slowed to a low rate. The films were flexible.

The glass tank was then drained and the activated foils rinsed twice inthe tank with deionized (DI) water. The smaller of the two pieces offoil was rinsed extensively under a deionized water tap and cut into twopieces. One piece was stored in a glass jar under water and the otherdried overnight at 120° C. under 24″ Hg (610 mm Hg) vacuum with nitrogenpurge. The larger of the original two pieces of foil was used for copperplating in Example 6.

Activated catalyst scraped from the foil had the following normalizedmetal content as determined by ICP-MS: 90.5% Ni, 9.4% Al and 0.16% Fe.The activation of the Raney nickel alloy-coated foils and observationsare summarized in Table 1 below.

TABLE 1 Time (min) Temp (° C.) Notes 0 −4 Time zero is the time ofaddition of NaOH and water 1 +8 Slow bubbling 2 +11 15 +9 40 +5 Icemelted, bubbling primarily from bottom of films 60 +5 Bubblingaccelerating 105 +7 Bubbling still vigorous 165 +11 Bubble-rich zoneabout 4 cm from bottom of the films 300 +21 Still bubbling, foils stillstiff, alloy surface is dark 360 +20→85 Liquid drained and hot diluteNaOH added, vigorous H₂ evolution, declining somewhat over time 380 75600 g of 50% NaOH added, H₂ evolution increases 420 58 Bubbling almostover, films are flexible, tank drained

EXAMPLE 6 Copper Plating of Activated Raney Nickel Alloy Film on NickelFoil

This example describes the copper plating of the activated Raney nickelalloy film on nickel foil prepared in Example 5. The larger piece of theactivated foil (17 cm×12 cm) was rinsed under the deionized water tapand transferred to a 1 liter beaker. It was then completely submerged indeionized water to protect it from air and held overnight.

In order to avoid damaging the foil, a magnetic stirrer (Ikamag REO) wasused instead of an overhead stirrer. The stir bar was weakly attractedto the film due to the ferromagnetism of nickel, but the stirrer had amagnet sufficiently powerful to keep the stir bar in the center of thebeaker, while the foil was coiled to conform roughly to the beaker wallwith the Raney surface facing inward.

CuSO₄.5H₂O (6.21 g, 20% by weight copper with respect to the activatedRaney film as calculated above), Versene 100 (27.4 g, 1.1 equivalents ofNa₄EDTA based on copper in the plating bath) and deionized water (700ml) were combined and sparged with nitrogen. The beaker containing thefoil was drained and the copper solution added immediately. The beakerwas topped off with deionized water (about 200 ml, not nitrogen-sparged)in order to completely submerge the foil. 2.5N NaOH (15 ml, 1.5equivalents) was added dropwise while stirring for 48 minutes. The pHrose from 11.7 to 12.7. The activated side of the foil acquired a richcopper color. The blue supernatant was decanted and the beaker wrappedwith heating tape.

CuSO₄.5H₂O (7.76 g, 25% by weight copper with respect to the activatedRaney film) was dissolved in water (100 ml) and added to the droppingfunnel. A hot mixture of 50% gluconic acid (37 g, 3 equivalents), 2.5NNaOH (12 ml) and water (400 ml) was added to cover the foil (about 500ml). The mixture was nitrogen-sparged. The initial temperature was 45°C. and the initial pH was 3.3. Power was applied to the heating tape,and the copper solution added dropwise over 70 minutes while stirring.The solution grew an increasingly deep green. The final pH was 3.2 andthe final temperature was 71° C. The green supernatant was decanted andthe bright copper-colored foil rinsed and stored in deionized water. Theback (foil) side also was copper-plated.

Catalyst scraped from the foil had the following normalized metalcontent as determined by ICP-MS: 48.4% Ni, 47.0% Cu, 4.50% Al and 0.11%Fe. Based on elemental analysis data, the foil comprised about 0.046g/cm² of activated catalyst.

EXAMPLE 7 Ethanol Reforming Using Copper-Plated Raney Nickel Alloy Filmon Nickel Foil

This example describes testing of the copper-plated Raney nickel alloyfilm catalyst on nickel foil prepared in Example 6 for ethanol reformingactivity. A schematic of the reforming apparatus used for activitytesting is shown in FIG. 5 and described by Morgenstern et al. in “LowTemperature Reforming of Ethanol over Copper-Plated Raney Nickel: A NewRoute to Sustainable Hydrogen for Transportation,” Energy and Fuels,Vol. 19, No. 4, pp. 1708-1716 (2005).

A rectangle (11 cm×6 cm, 5.99 g wet) was cut from the center of thecopper-plated foil prepared in Example 6 and the uncoated edges weretrimmed off. The rectangle was coiled tightly lengthwise (i.e., to makea cylinder 6 cm long) and inserted into the reforming tube having aninside diameter of 0.375 in. (9.5 mm) of the apparatus with the catalystside facing inward. The coil fit easily in the tube and around the 0.125in. (3.2 mm) thermocouple located in the center of the tube. Thethermocouple did not extend the full 6 cm, so the open space waspartially filled with a 0.125-inch (3.2 mm) diameter stainless steelrod. The reformer was connected to the preheater and flushed withnitrogen overnight.

The reformer was brought to temperature under nitrogen flow prior tobeginning the ethanol-water feed. A mixture of 70% ethanol in water(mole H₂O:mole ethanol=1.1) was used as the feed solution and preparedby adding water to 200 proof ethanol (available from Aaper, Shelbyville,Ky.). The ethanol-water feed solution was delivered to the reformer withan Isco 500D syringe pump.

The catalyst was maintained under substantially isothermal conditions(within 1° C.) by the use of two heaters. The ethanol-water feed flowedupward through a preheater, which was controlled to maintain the feedtemperature at the entrance to the catalyst bed at the desired value. Acable heater, aligned with the catalyst bed, supplied the heat ofreaction and kept the exit temperature equal to the inlet temperature ofthe catalyst bed.

A six-port Valco valve was used to direct samples of the reformereffluent to the injection port of a gas chromatograph (Varian 3400 GC)equipped with a thermal conductivity detector. A 10 ft.×0.125 in.×0.085in. (3.05 m×3.2 mm×2.2 mm) Hayesep D packed column (Alltech) was used.

The flowrate and temperature were varied for the first 30 hours until anoperating point of 0.1 ml/min (corresponding to 1.318 mmoles ofethanol/min) and 320° C. was chosen. Under these conditions, about 10%ethanol remained unreacted, allowing us to monitor deactivation of thecatalyst. There was evidence of some methanation, likely catalyzed bythe exposed nickel on the side of the foil opposite the catalyst. In anautomotive reformer, the exposed nickel on the back of the foil wouldnot be in contact with the ethanol feed mixture (it would be in contactwith the exhaust), so this observation is not a concern.

After about 100 hours on stream, pressure began to increase and theexperiment was terminated. Prior to this time, the inlet pressure hadbeen less than 3 psig (155 mm Hg gauge). The pressure rise was theresult of some catalyst particles detaching from the foil and creating apartial blockage downstream.

The yield of the low-temperature reforming products during the periodwhen the reformer was operated at 320° C. with a feed rate of 0.1 ml/minand the pressure below 3 psig are set forth in Table 2 below. Conversionwas steady, indicating that the catalyst was stable.

TABLE 2 Yield of Low-Temperature Reforming Products During EthanolReforming at 320° C., 0.1 ml/min of 70% Ethanol Feed Mixture Hours CH₄CO CO₂ CH₃CHO CH₃CH₂OH 30 94.6% 53.7% 22.6% 7.9% 6.6% 40 103.5% 53.7%25.7% 2.4% 6.2% 50 103.4% 46.0% 24.9% 2.6% 10.2% 60 110.0% 39.1% 32.8%1.8% 7.3% 70 110.5% 39.6% 29.9% 1.6% 8.4% 80 111.6% 31.8% 38.7% 1.4%7.6%

Note that methane yields and mass balances based on methane can exceed100% due to analytical uncertainties and the methanation of CO byreaction with hydrogen to produce methane and water. Note also that thehydrogen yield is omitted from the Table 2. Although hydrogen wasmeasured directly in the gas chromatograph, thermal conductivitydetectors exhibit low sensitivity for hydrogen compared tocarbon-containing molecules resulting in more scatter in the data.Accordingly, hydrogen yield can be calculated more accurately from theyield of carbon-containing compounds such as carbon monoxide, carbondioxide and methane.

EXAMPLE 8 Copper Plating of Activated Raney Nickel Alloy Film on NickelFoil Utilizing Reversible Passivation of the Back of the Foil

Electron microscopy of the copper-plated Raney nickel alloy filmcatalyst on nickel foil prepared in Example 6 revealed that copperplated heavily onto the back of the foil (i.e., on the side opposite theRaney nickel catalyst), but copper penetrated less than about 10 μm intothe Raney nickel film layer. Nickel can easily be oxidatively removedfrom the interior of the Raney nickel film, but copper plating of thefoil surface, which is predominantly plating of copper onto copper, isfaster than plating of the interior of the Raney nickel film.Penetration of copper plating is hindered by diffusion and by the factthat the nickel surface is likely oxidized during plating.

In this Example, copper plating on the back of the foil was eliminatedby coating it with an insulating layer of an acrylic polymer. Thepolymer layer was then stripped after the copper plating procedure hadbeen completed. The insulating layer was applied using Sprayon S00611Clear Lacquer Electrical Spray, a fast drying, waterproof insulatingcomponent sealer (Diversified Brands, Cleveland, Ohio, available fromdistributors such as Grainger). Sprayon S00611 consists of a proprietaryacrylic polymer in mixed organic solvents, primarily acetone, toluene,propane, and butane.

A piece (11 cm×9 cm) of Raney nickel alloy-coated foil (CERAM,Stoke-on-Trent, Great Britain) activated in accordance with theprocedure in Example 5 was copper plated using the procedure describedbelow. The activated foil had been stored under water after activation.The foil was removed from the water, patted dry with tissues, laidfoil-side-up on a clean tissue, and sprayed with Sprayon S00611. Thefoil was then transferred to a bed of thoroughly soaked tissues in aglass beaker where it was laid down, again foil side up. The purpose ofthe tissues was to keep the Raney nickel side wet and protected fromoxidation while the acrylic film dried on the foil.

The target copper concentration in the catalyst phase was 35% by weightwith respect to the activated Raney film. CuSO₄.5H₂O (6.36 g), Versene100 (27.6 g, 1.1 equiv. of Na₄EDTA) and deionized water (450 ml) werecombined and added to a beaker equipped with a stir bar and containingthe acrylic polymer-coated, Raney nickel foil. 2.5N NaOH (13 ml, 1.3equiv.) was added dropwise more quickly than usual so as to be fasterthan any deterioration of the acrylic layer. The NaOH addition wasperformed over 7 minutes while stirring. The pH rose from 11.7 to 12.6.The dark blue supernatant was decanted. The back side of the foil (i.e.,opposite the activated Raney side) was free of copper deposition.

The beaker was wrapped with heating tape and the decanted liquidreplaced with a warm (34° C.) mixture of 50% gluconic acid (9.8 g, 1.0equivalent with respect to copper in the first step) and water (500 ml).The pH was 2.4. Power was applied to the heating tape and stirringinitiated in order to disproportionate the Cu₂O. The temperature reached60° C. in ten minutes and was maintained at that level until the end ofthis step of the plating experiment.

Stirring was discontinued after 45 minutes. At this point, the liquidwas nearly colorless, the pH was 2.3 and the temperature was 60° C. Thefoil was removed from the beaker, rinsed with deionized water and storedin a beaker under deionized water. There was no sign of copper platingon the back of the foil.

The next day, the water was drained and a small (approximately 1 cm×1cm) sample cut from the foil. The foil sample was then returned to thebeaker and hot (71° C.) xylenes (500 ml) added. Power was applied to theheating tape and the beaker was stirred for 30 minutes in order toremove the acrylic polymer layer. The final temperature was 105° C. Thexylenes were poured off and the foil rinsed with deionized water andstored in a glass bottle under deionized water.

The catalyst side of the foil was almost black with only a few faintpatches of faint copper color. This indicates that copper was notpredominantly deposited on the surface of the Raney nickel film, butrather penetrated into it.

Another sample (approximately 1 cm×1 cm) was obtained and both sampleswere dried overnight in a vacuum oven at 120° C. under 24″ Hg (610 mmHg) vacuum with nitrogen purge.

EXAMPLE 9 Preparation of a Copper-Nickel Catalyst on a Silica Support

The plating method of this Example is similar to that in Example 2,however the copper addition in the second step of Example 2 is omittedin order to keep the pH above 2. This was done to avoid dissolution ofsilica. All of the copper was added in the first step, and the secondstep was performed at acidic pH to disproportionate copper deposited inthe first step (which is thought to be predominantly in the form ofCu₂O) via the following reaction.Cu₂O+2H⁺+Ni⁰→2Cu⁰+Ni²⁺+H₂O

The substrate used was 70% by weight nickel on silica, reduced andstabilized, from Acros Organics, lot A013077801. The substrate (40 g)was added to a beaker (1 liter) containing a nitrogen-sparged mixture ofCuSO₄.5H₂O (33.0 g; 21 wt % Cu with respect to substrate, 30 wt % withrespect to nickel), Versene 100 (145 g; 1.1 equiv. of Na₄EDTA, Dow viaSpectrum) and water (300 ml). NaOH (58 ml; 1.1 equiv.; 2.5N) was thenadded dropwise over 24 minutes while stirring with an overhead stirrerunder a nitrogen atmosphere. The pH rose from 11.6 to 13.4. The catalystwas filtered off and rinsed with deionized water. The filtrate was blue.

The recovered catalyst was returned to the beaker which was wrapped withheating tape. A hot solution of lactic acid (18 g; 1.5 equiv. withrespect to copper added; Aldrich,) in water (300 ml) was added, powerwas applied to the heating tape, and the slurry was gently stirred for50 minutes under a nitrogen atmosphere. The initial pH was 2.4 and theinitial temperature was 53° C. At the end of this step, the pH had risento 6.2, indicating that the disproportionation had occurred. The finaltemperature was 62° C.

The catalyst was recovered by filtration and rinsed with deionizedwater. The filtrate exhibited a strong nickel green color. The catalystwas dried overnight at 120° C. under 24″ Hg (609 mm Hg) vacuum withnitrogen purge. Black catalyst (29.1 g) was recovered. No self-heatingwas observed.

EXAMPLE 10 Activity of Copper-Nickel on Silica Catalyst

The catalyst (2.5 g) of Example 9 was used to test the activity ofcopper-nickel silica supported catalysts using the same reformingapparatus used for activity testing in Example 7 and shown schematicallyin FIG. 5. A feed (of 0.1 ml/minute) of 70% ethanol and 30% water byvolume was used and the temperature was varied. The catalyst was activeat low temperature for the reforming of ethanol to H₂, CO, and CH₄.However, above 220° C., methanation occurred, likely catalyzed byunplated nickel.

This example also illustrates the efficacy of using Monel as a materialof construction for the preheater to supress coking. A new preheatertube fabricated from Monel was used during the run. No sign of cokingwas seen in the preheater. The backpressure never exceeded 6 psi and wasgenerally below 4 psi (206 mm Hg) during the run with no sign of anincrease. The run was continued for 194 hours with no operationaldifficulty.

Product distributions, in mol % relative to ethanol supplied areprovided in the Table 3, wherein the abbreviations “Acet” and “EtOH”represent acetaldehyde and ethanol, respectively. An Arrhenius plotbetween 185° C. and 210° C. provided an activation energy of 16.3kcal/mol, which is identical thermodynamic enthalpy for ethanoldehydrogenation. Thus, with this catalyst loading, ethanol conversion isthermodynamically limited below about 210° C.CH₃CH₂OH_((g))→CH₃CHO_((g))+H₂ ΔH_(f)=+16.27 kcal/mole

TABLE 3 Product Concentrations of Ethanol Reformed over a Copper-NickelSilica Supported Catalyst Temp (° C.) H₂ CO CH₄ CO₂ Acet EtOH 185 42.8%30.7% 33.9% 1.9% 6.1% 60.6% 190 54.0% 41.2% 45.7% 2.9% 5.3% 49.8% 19565.8% 51.4% 58.4% 4.3% 4.4% 38.5% 200 77.5% 61.2% 71.3% 6.1% 3.3% 27.4%205 88.6% 74.2% 90.9% 9.4% 2.5% 10.2% 210 98.6% 74.2% 101.9% 16.6% 2.1%1.6% 220 69.4% 72.3% 115.4% 12.4% 0.0% 0.0% 225 78.6% 54.2% 117.9% 27.9%0.0% 0.0% 230 7.6% 0.1% 148.4% 51.5% 0.0% 0.0%

Between about 220° C. and about 230° C., methanation activity increasesrapidly and by 230° C., methanation is nearly complete, with the overallstoichiometry shown by the reaction equations below. This corresponds toa shift from endothermic to exothermic chemistry. As a result, thermalinstability was encountered in this temperature range. As methanationchemistry began, it tended to heat the catalyst, further increasingmethanation. The temperature controller compensated by reducing heatinput, but temperature correction was slow and temperature oscillationswere observed.CH₃CH₂OH_((g))→CH₄+CO+H₂ ΔH_(f)=+11.72 kcal/mole2CH₃CH₂OH_((g))→3CH₄+CO₂ ΔH_(f)=−35.66 kcal/mole

Thus, copper-nickel catalysts on silica appear to be highly active atlow temperature, achieving thermodynamically-limited conversion, but areprone to methanation at higher temperatures.

EXAMPLE 11 Predicted Engine Performance Generated from CombustionModeling

Efficiency and emissions performance of several powertrain systems werecompared by combustion modeling using the “GT-POWER” simulation program.Simulated systems include internal combustion engines spark-ignited witha premixed charge and fueled by (1) gasoline, (2) hydrogen, (3)anhydrous ethanol and (4) ethanol reformate generated from contactinganhydrous ethanol with a reforming catalyst with copper at the surfaceof a thermally conductive metal supporting structure and without awater-gas shift. The combustion model used a one-dimensional, two zoneflame speed with an equilibrium gas composition. Performance wasevaluated at steady-state.

Optimized Air/Fuel Equivalency Ratio

The models were run under lean conditions as engine power can bedetermine from fuel flow without varying the air flow and pumping lossesassociated with throttling are avoided. The air:fuel equivalence ratiosused for the hydrogen (H₂) and ethanol reformate (Ref.) enginesimulations at a range of brake mean effective pressures (BMEP) areshown in Table 4 below. These lean limits were determined by increasingthe air:fuel ratio in the simulation until the predicted efficiencybecame unfavorable or combustion parameters such as burn time, totalmass fraction burned, etc., became unfavorable.

TABLE 4 Optimized lean Air/fuel Equivalence Ratios used in theSimulations BMEP (bar) 6 H₂: 2.20 H₂: 2.20 H₂: 2.20 Ref: 2.00 Ref: 2.00Ref: 2.00 4 H₂: 2.86 H₂: 2.86 H₂: 2.86 Ref: 2.00 Ref: 2.00 Ref: 2.00 2H₂: 3.12 H₂: 3.12 H₂: 3.12 Ref: 2.00 Ref: 2.00 Ref: 2.00   0.5 H₂: 3.85Ref: 2.00 Engine Speed 850 1500 2200 3000 (RPM)At low load conditions the simulated reformate engine must be operatedwith slight throttling. When the reformate engine is operatedunthrottled at low fuel feed rates, dilution of the fuel with air isquite high. The simulation indicated that partial throttling at low fuelrates was necessary to maintain sufficiently rapid combustion.Optimized Engine Parameters

Engine parameters used in the simulation were optimized for each systemto achieve maximum efficiency while meeting NO_(x) emissions standards(CA LEV II 50k, 0.05 g/mile, 14 ppm average over the drive cycle).First, the highest allowable compression ratio was found by increasingthe compression ratio incrementally until knock was predicted. Next, thespark timing for maximum brake torque at the operating points ofinterest was established. The parameters were then further optimized forhigh efficiency and adjusted to meet NO_(x) emissions standards based onsimulated emissions results for each engine configuration except thereformate engine. In the case of the reformate engine, previous tests oflean hydrogen operation in the laboratory suggested that the air:fuelmixture will be lean enough to produce the required low levels of NO_(x)of the CA LEV II 50 k emissions standards.

The key engine parameters used in the simulations are shown below inTable 5.

TABLE 5 Key Engine Parameters used in the Simulation CompressionThree-way Engine Ratio Throttled? Fuel/Air Mixture Catalyst? Boosted?Gasoline 9 Yes Stoichiometric Yes No ICE Hydrogen 14.5 No Lean (SeeTable 4) Not Yes ICE Necessary Anhydrous 14 Yes Stoichiometric Yes NoEthanol ICE Anhydrous 14 Partial Lean (See Table 4) Not Yes EthanolNecessary Reformate ICE

Each engine system was optimized to compare best-case scenarios for eachfuel using a port fuel injected internal combustion engine. Technologiesthat would have given across the board improvements such as enginedown-sizing were not considered. The ethanol and reformateconfigurations use anhydrous ethanol without a denaturant such asgasoline. In practice, a denaturant may reduce the actual compressionratios achieved.

As shown in Table 5, optimizing each simulated engine system forpredicted high efficiency and predicted low NO_(x) resulted in varioussystem operating strategies. Gasoline and ethanol systems were simulatedat stoichiometric air:fuel ratios to allow for three-way catalyst (i.e.catalytic converter) operation, while hydrogen and reformate engineswere simulated lean at part load conditions to reduce pumping lossesfrom throttling and were maintained at air:fuel ratios that rendered athree-way catalyst unnecessary to meet emissions standards. Simulatedhydrogen and reformate engines were boosted to provide a better poweroutput during lean operation. Other adjustments were made in thesimulation to ensure smooth predicted engine operation, including a 25%increase in spark size for the reformate engine.

Results

The results of the simulations are shown in FIGS. 6 and 7. FIG. 6depicts the NO_(x) emissions predictions of the simulation for thegasoline, hydrogen and ethanol systems. The reformate system data wasgenerated from previously tested cases of lean hydrogen operation. Ascan be seen from FIG. 6 and as designed for in the simulation, NO_(x)emissions for each configuration are maintained below CA LEV II 50 kemissions standards, i.e., below about 14 ppm. In practice, NO_(x)emissions would be expected to be higher, perhaps by an order ofmagnitude, than the simulation due to the two-zone flame assumption ofthe simulation. The high load case where BMEP is equal to 6 bar andwhere emissions are the highest is shown in FIG. 6. The Figure indicatesthat, over a drive cycle, predicted average NO_(x) emissions areexpected to be below the limit of 14 ppm.

Predicted exhaust temperatures for the reformate system are shown inFIG. 7. Reformate engine exhaust temperature is predicted to remainhigh, i.e. at least about 400° C., at all conditions except idle.Accordingly, thermal contact between the exhaust gas and the reformershould be sufficient to maintain reformer operating temperatures of atleast about 300° C.

Calculated peak efficiencies for the engine systems are shown in FIG. 8.As can be seen from the Figure, the anhydrous ethanol system results inpredicted efficiency improvements over the gasoline system. Theanhydrous ethanol reformate system further increases those benefitslargely due to the 7% increase in LHV of the fuel as a result ofreforming.

The design power output for each engine was assumed to be 108 kW,however the majority of drive-cycle power is less than 50 kW, with amaximum load of 6 bar and maximum speed of 6000 RPM. The efficienciesshown in FIG. 8 are best-case efficiencies. The engine will not be atpeak efficiency at all points of the drive cycle. The energy requiredfor boosting was not taken into account in the hydrogen and reformatecases however this should not result in a large efficiency drop if theengine is properly turbocharged.

In view of the above, it will be seen that the several objects of theinvention are achieved and other advantageous results attained.

As various changes could be made in the above methods and constructionswithout departing from the scope of the invention, it is intended thatall matter contained in the above description and shown in theaccompanying drawings shall be interpreted as illustrative and not in alimiting sense.

When introducing elements of the present invention or the preferredembodiments(s) thereof, the articles “a”, “an”, “the” and “said” areintended to mean that there are one or more of the elements. The terms“comprising”, “including”, “containing” and “having” are intended to beinclusive and mean that there may be additional elements other than thelisted elements.

1. A process for producing mechanical or electrical power, the processcomprising: contacting a feed gas mixture comprising an ethanol fuelwith a reforming catalyst in a reforming reaction zone to produce aproduct reformate gas mixture comprising hydrogen and methane;introducing a prechamber gas mixture comprising oxygen and ethanol fuelinto a combustion prechamber in fluid communication with a combustionchamber of an internal combustion engine; introducing an intake gasmixture comprising oxygen and product reformate gas mixture into thecombustion chamber; igniting the prechamber gas mixture in thecombustion prechamber to generate a flame jet and cause combustion ofthe intake gas mixture introduced into the combustion chamber, therebyproducing an exhaust gas effluent; and utilizing the energy ofcombustion for the generation of mechanical or electrical power.
 2. Aprocess for producing mechanical or electrical power in a power systemcomprising an internal combustion engine utilizing a four-stroke powercycle, the internal combustion engine comprising at least one combustionchamber and an intake valve in fluid communication with the combustionchamber and having an open and closed position, the internal combustionengine being capable of producing a combustion chamber expansion ratiothat is greater than the corresponding compression ratio, the processcomprising: introducing an intake gas mixture comprising oxygen and afuel selected from the group consisting of gasoline, alcohol, reformedalcohol and blends thereof into the combustion chamber of the internalcombustion engine; controlling the length of time the intake valveremains in the open position during the power cycle in response to thetype of fuel introduced into the combustion chamber such that thecompression ratio does not exceed about 10.5 when the fuel comprises atleast about 90% by volume gasoline and is greater than about 12 when thefuel comprises greater than about 85% by volume alcohol or greater thanabout 10% by volume reformed alcohol; combusting the intake gas mixture;and utilizing the energy of combustion for the generation of mechanicalor electrical power.
 3. The process as set forth in claim 2 wherein thelength of time the intake valve remains open is controlled such that thecompression ratio does not exceed about 10.5 when the fuel comprises atleast about 90% by volume gasoline and is greater than about 12 when thefuel comprises greater than about 85% by volume ethanol or greater thanabout 10% by volume reformed ethanol.